diff --git a/include/audacity/ModuleInterface.h b/include/audacity/ModuleInterface.h
index 1bdecec42..fd95811f1 100644
--- a/include/audacity/ModuleInterface.h
+++ b/include/audacity/ModuleInterface.h
@@ -84,7 +84,7 @@ public:
    // This function returns nonempty only when that is the case, and lists
    // the possible extensions of such files (an empty string in a nonempty
    // array means any file is a candidate).
-   virtual FileExtensions GetFileExtensions() = 0;
+   virtual const FileExtensions &GetFileExtensions() = 0;
 
    // Returns empty, or else, where to copy a plug-in file or bundle.
    // Drag-and-drop is supported only if GetFileExtensions() returns nonempty and
diff --git a/include/audacity/Types.h b/include/audacity/Types.h
index 985435322..5027e7589 100644
--- a/include/audacity/Types.h
+++ b/include/audacity/Types.h
@@ -46,9 +46,27 @@
 #include <type_traits>
 #include <vector>
 #include <wx/debug.h> // for wxASSERT
+#include <wx/string.h> // type used in inline function
+#include <wx/version.h> // for wxCHECK_VERSION
 
 class wxString;
 
+#if !wxCHECK_VERSION(3, 1, 0)
+// For using std::unordered_map on wxString
+namespace std
+{
+   template<typename T> struct hash;
+   template<> struct hash< wxString > {
+      size_t operator () (const wxString &str) const // noexcept
+      {
+         auto stdstr = str.ToStdWstring(); // no allocations, a cheap fetch
+         using Hasher = hash< decltype(stdstr) >;
+         return Hasher{}( stdstr );
+      }
+   };
+}
+#endif
+
 // ----------------------------------------------------------------------------
 // TODO:  I'd imagine this header may be replaced by other public headers. But,
 //        to try and minimize more changes to the base code, we can use this
diff --git a/src/AudacityApp.cpp b/src/AudacityApp.cpp
index ee732c880..313f5731e 100644
--- a/src/AudacityApp.cpp
+++ b/src/AudacityApp.cpp
@@ -1829,9 +1829,8 @@ bool AudacityApp::InitTempDir()
       }
 
       // Only want one page of the preferences
-      DirectoriesPrefsFactory directoriesPrefsFactory;
       PrefsDialog::Factories factories;
-      factories.push_back(&directoriesPrefsFactory);
+      factories.push_back(DirectoriesPrefsFactory());
       GlobalPrefsDialog dialog(NULL, factories);
       dialog.ShowModal();
 
diff --git a/src/AutoRecovery.h b/src/AutoRecovery.h
index ec49af72a..1be3c6128 100644
--- a/src/AutoRecovery.h
+++ b/src/AutoRecovery.h
@@ -17,6 +17,7 @@
 #include <wx/mstream.h> // member variables
 
 #include <unordered_map>
+#include "audacity/Types.h"
 
 class wxFFile;
 class AudacityProject;
diff --git a/src/HistoryWindow.cpp b/src/HistoryWindow.cpp
index d005787bb..803c50133 100644
--- a/src/HistoryWindow.cpp
+++ b/src/HistoryWindow.cpp
@@ -142,7 +142,6 @@ HistoryWindow::HistoryWindow(AudacityProject *parent, UndoManager *manager):
    S.EndVerticalLay();
    // ----------------------- End of main section --------------
 
-   DoUpdate();
    mList->SetMinSize(mList->GetSize());
    Fit();
    SetMinSize(GetSize());
@@ -182,6 +181,13 @@ void HistoryWindow::UpdateDisplay(wxEvent& e)
       DoUpdate();
 }
 
+bool HistoryWindow::Show( bool show )
+{
+   if ( show && !IsShown())
+      DoUpdate();
+   return wxDialogWrapper::Show();
+}
+
 void HistoryWindow::DoUpdate()
 {
    int i;
diff --git a/src/HistoryWindow.h b/src/HistoryWindow.h
index 6aba7b3d5..f8b987a4f 100644
--- a/src/HistoryWindow.h
+++ b/src/HistoryWindow.h
@@ -28,6 +28,8 @@ class HistoryWindow final : public wxDialogWrapper {
    HistoryWindow(AudacityProject * parent, UndoManager *manager);
 
    void UpdateDisplay(wxEvent &e);
+   
+   bool Show( bool show = true ) override;
 
  private:
    void OnAudioIO(wxCommandEvent & evt);
diff --git a/src/Languages.cpp b/src/Languages.cpp
index 8bc2ab290..becd2f273 100644
--- a/src/Languages.cpp
+++ b/src/Languages.cpp
@@ -33,6 +33,8 @@
 #include "Audacity.h"
 #include "Languages.h"
 
+#include "audacity/Types.h"
+
 #include <wx/defs.h>
 #include <wx/intl.h>
 #include <wx/textfile.h>
diff --git a/src/MemoryX.h b/src/MemoryX.h
index 5b9bab279..afde54a06 100644
--- a/src/MemoryX.h
+++ b/src/MemoryX.h
@@ -637,22 +637,6 @@ make_iterator_range( const Container &container )
    return { container.begin(), container.end() };
 }
 
-#if !wxCHECK_VERSION(3, 1, 0)
-// For using std::unordered_map on wxString
-namespace std
-{
-   template<typename T> struct hash;
-   template<> struct hash< wxString > {
-      size_t operator () (const wxString &str) const // noexcept
-      {
-         auto stdstr = str.ToStdWstring(); // no allocations, a cheap fetch
-         using Hasher = hash< decltype(stdstr) >;
-         return Hasher{}( stdstr );
-      }
-   };
-}
-#endif
-
 // A utility function building a container of results
 template< typename Container, typename Iterator, typename Function >
 Container transform_range( Iterator first, Iterator last, Function &&fn )
diff --git a/src/ModuleManager.cpp b/src/ModuleManager.cpp
index 531608c39..e0bbeda29 100755
--- a/src/ModuleManager.cpp
+++ b/src/ModuleManager.cpp
@@ -509,8 +509,7 @@ void ModuleManager::FindAllPlugins(PluginIDs & providers, PluginPaths & paths)
    {
       PluginID providerID = modIDs[i];
 
-      ModuleInterface *module =
-         static_cast<ModuleInterface *>(CreateProviderInstance(providerID, modPaths[i]));
+      auto module = CreateProviderInstance(providerID, modPaths[i]);
 
       if (!module)
          continue;
@@ -553,7 +552,7 @@ bool ModuleManager::RegisterEffectPlugin(const PluginID & providerID, const Plug
    return nFound > 0;
 }
 
-ComponentInterface *ModuleManager::CreateProviderInstance(const PluginID & providerID,
+ModuleInterface *ModuleManager::CreateProviderInstance(const PluginID & providerID,
                                                       const PluginPath & path)
 {
    if (path.empty() && mDynModules.find(providerID) != mDynModules.end())
diff --git a/src/ModuleManager.h b/src/ModuleManager.h
index 9c67f776e..4276e08cb 100644
--- a/src/ModuleManager.h
+++ b/src/ModuleManager.h
@@ -102,7 +102,7 @@ public:
    bool RegisterEffectPlugin(const PluginID & provider, const PluginPath & path,
                        wxString &errMsg);
 
-   ComponentInterface *CreateProviderInstance(const PluginID & provider, const PluginPath & path);
+   ModuleInterface *CreateProviderInstance(const PluginID & provider, const PluginPath & path);
    ComponentInterface *CreateInstance(const PluginID & provider, const PluginPath & path);
    void DeleteInstance(const PluginID & provider, ComponentInterface *instance);
 
diff --git a/src/PluginManager.cpp b/src/PluginManager.cpp
index 019f8729c..e460e09e7 100644
--- a/src/PluginManager.cpp
+++ b/src/PluginManager.cpp
@@ -1787,7 +1787,7 @@ bool PluginManager::DropFile(const wxString &fileName)
          continue;
 
       const auto &ff = module->InstallPath();
-      auto extensions = module->GetFileExtensions();
+      const auto &extensions = module->GetFileExtensions();
       if ( !ff.empty() &&
           extensions.Index(src.GetExt(), false) != wxNOT_FOUND ) {
          wxString errMsg;
diff --git a/src/ShuttleGui.cpp b/src/ShuttleGui.cpp
index 9a210dab3..b002f0112 100644
--- a/src/ShuttleGui.cpp
+++ b/src/ShuttleGui.cpp
@@ -2392,170 +2392,3 @@ void ShuttleGuiBase::SetSizeHints( const wxArrayStringEx & items )
 
    SetSizeHints( mpLastWind, items );
 }
-
-/********************************* GetDefinition ******************************/
-
-ShuttleGuiGetDefinition::ShuttleGuiGetDefinition(
-   wxWindow * pParent,CommandMessageTarget & target )
-: ShuttleGui( pParent, eIsGettingMetadata ),
-  CommandMessageTargetDecorator( target )
-{
-
-}
-ShuttleGuiGetDefinition::~ShuttleGuiGetDefinition(void)
-{
-}
-
-wxCheckBox * ShuttleGuiGetDefinition::TieCheckBox(
-   const wxString &Prompt,
-   const wxString &SettingName,
-   const bool bDefault) 
-{ 
-   StartStruct();
-   AddItem( SettingName, "id" );
-   AddItem( Prompt, "prompt" );
-   AddItem( "bool", "type" );
-   AddBool( bDefault, "default"  );
-   EndStruct();
-   return ShuttleGui::TieCheckBox( Prompt, SettingName, bDefault );
-}
-wxCheckBox * ShuttleGuiGetDefinition::TieCheckBoxOnRight(
-   const wxString &Prompt,
-   const wxString &SettingName,
-   const bool bDefault) 
-{
-   StartStruct();
-   AddItem( SettingName, "id" );
-   AddItem( Prompt, "prompt" );
-   AddItem( "bool", "type" );
-   AddBool( bDefault, "default"  );
-   EndStruct();
-   return ShuttleGui::TieCheckBoxOnRight( Prompt, SettingName, bDefault );
-}
-wxChoice * ShuttleGuiGetDefinition::TieChoice(
-   const wxString &Prompt,
-   const wxString &SettingName,
-   const wxString &Default,
-   const wxArrayStringEx &Choices,
-   const wxArrayStringEx & InternalChoices )
-{
-   StartStruct();
-   AddItem( SettingName, "id" );
-   AddItem( Prompt, "prompt" );
-   AddItem( "enum", "type" );
-   AddItem( Default, "default"  );
-   StartField( "enum" );
-   StartArray();
-   for( size_t i=0;i<Choices.size(); i++ )
-      AddItem( InternalChoices[i] );
-   EndArray();
-   EndField();
-   EndStruct();
-   return ShuttleGui::TieChoice( Prompt, SettingName, Default, Choices, InternalChoices );
-}
-wxChoice * ShuttleGuiGetDefinition::TieChoice(
-   const wxString &Prompt,
-   const wxString &SettingName,
-   const int Default,
-   const wxArrayStringEx & Choices,
-   const std::vector<int> & InternalChoices)
-{
-   // Should no longer come here!
-   // Choice controls in Preferences that really are exhaustive choices among
-   // non-numerical options must now encode the internal choices as strings,
-   // not numbers.
-   wxASSERT(false);
-
-   // But if we do get here anyway, proceed sub-optimally as before.
-   StartStruct();
-   AddItem( SettingName, "id" );
-   AddItem( Prompt, "prompt" );
-   AddItem( "enum", "type" );
-   AddItem( Default, "default"  );
-   StartField( "enum" );
-   StartArray();
-   for( size_t i=0;i<Choices.size(); i++ )
-      AddItem( Choices[i] );
-   EndArray();
-   EndField();
-   EndStruct();
-   return ShuttleGui::TieChoice( Prompt, SettingName, Default, Choices, InternalChoices );
-}
-wxChoice * ShuttleGuiGetDefinition::TieNumberAsChoice(
-   const wxString &Prompt,
-   const wxString &SettingName,
-   const int Default,
-   const wxArrayStringEx & Choices,
-   const std::vector<int> & InternalChoices)
-{
-   // Come here for controls that present non-exhaustive choices among some
-   //  numbers, with an associated control that allows arbitrary entry of an
-   // "Other..."
-   StartStruct();
-   AddItem( SettingName, "id" );
-   AddItem( Prompt, "prompt" );
-   AddItem( "number", "type" ); // not "enum" !
-   AddItem( Default, "default"  );
-   EndStruct();
-   return ShuttleGui::TieNumberAsChoice(
-      Prompt, SettingName, Default, Choices, InternalChoices );
-}
-wxTextCtrl * ShuttleGuiGetDefinition::TieTextBox(
-   const wxString &Prompt,
-   const wxString &SettingName,
-   const wxString &Default,
-   const int nChars) 
-{
-   StartStruct();
-   AddItem( SettingName, "id" );
-   AddItem( Prompt, "prompt" );
-   AddItem( "string", "type" );
-   AddItem( Default, "default"  );
-   EndStruct();
-   return ShuttleGui::TieTextBox( Prompt, SettingName, Default, nChars );
-}
-wxTextCtrl * ShuttleGuiGetDefinition::TieNumericTextBox(
-   const wxString & Prompt,
-   const wxString & SettingName,
-   const double & Default,
-   const int nChars) 
-{
-   StartStruct();
-   AddItem( SettingName, "id" );
-   AddItem( Prompt, "prompt" );
-   AddItem( "number", "type" );
-   AddItem( Default, "default"  );
-   EndStruct();
-   return ShuttleGui::TieNumericTextBox( Prompt, SettingName, Default, nChars );
-}
-wxSlider * ShuttleGuiGetDefinition::TieSlider(
-   const wxString & Prompt,
-   const wxString & SettingName,
-   const int iDefault,
-   const int max,
-   const int min) 
-{
-   StartStruct();
-   AddItem( SettingName, "id" );
-   AddItem( Prompt, "prompt" );
-   AddItem( "number", "type" );
-   AddItem( iDefault, "default"  );
-   EndStruct();
-   return ShuttleGui::TieSlider( Prompt, SettingName, iDefault, max, min );
-}
-wxSpinCtrl * ShuttleGuiGetDefinition::TieSpinCtrl(
-   const wxString &Prompt,
-   const wxString &SettingName,
-   const int Value,
-   const int max,
-   const int min) 
-{
-   StartStruct();
-   AddItem( SettingName, "id" );
-   AddItem( Prompt, "prompt" );
-   AddItem( "number", "type" );
-   AddItem( Value, "default"  );
-   EndStruct();
-   return ShuttleGui::TieSpinCtrl( Prompt, SettingName, Value, max, min );
-}
-
diff --git a/src/ShuttleGui.h b/src/ShuttleGui.h
index 76a5277b4..12390c957 100644
--- a/src/ShuttleGui.h
+++ b/src/ShuttleGui.h
@@ -22,9 +22,6 @@
 
 #include "WrappedType.h"
 
-// For ShuttleGuiGetDefinitions.
-#include "commands/CommandTargets.h"
-
 class ChoiceSetting;
 
 class wxArrayStringEx;
@@ -443,68 +440,4 @@ public:
    teShuttleMode GetMode() { return  mShuttleMode; };
 };
 
-
-/**************************************************************************//**
-\brief Shuttle that retrieves a JSON format definition of a command's parameters.
-********************************************************************************/
-class ShuttleGuiGetDefinition : public ShuttleGui, public CommandMessageTargetDecorator
-{
-public:
-   ShuttleGuiGetDefinition(wxWindow * pParent,CommandMessageTarget & target );
-   virtual ~ShuttleGuiGetDefinition();
-
-   wxCheckBox * TieCheckBox(
-      const wxString &Prompt,
-      const wxString &SettingName,
-      const bool bDefault) override;
-   wxCheckBox * TieCheckBoxOnRight(
-      const wxString &Prompt,
-      const wxString &SettingName,
-      const bool bDefault) override;
-   wxChoice * TieChoice(
-      const wxString &Prompt,
-      const wxString &SettingName,
-      const wxString &Default,
-      const wxArrayStringEx &Choices,
-      const wxArrayStringEx & InternalChoices ) override;
-
-   // An assertion will be violated if this override is reached!
-   wxChoice * TieChoice(
-      const wxString &Prompt,
-      const wxString &SettingName,
-      const int Default,
-      const wxArrayStringEx & Choices,
-      const std::vector<int> & InternalChoices) override;
-
-   wxChoice * TieNumberAsChoice(
-      const wxString &Prompt,
-      const wxString &SettingName,
-      const int Default,
-      const wxArrayStringEx & Choices,
-      const std::vector<int> & InternalChoices) override;
-
-   wxTextCtrl * TieTextBox(
-      const wxString &Prompt,
-      const wxString &SettingName,
-      const wxString &Default,
-      const int nChars) override;
-   wxTextCtrl * TieNumericTextBox(
-      const wxString & Prompt,
-      const wxString & SettingName,
-      const double & Default,
-      const int nChars) override;
-   wxSlider * TieSlider(
-      const wxString & Prompt,
-      const wxString & SettingName,
-      const int iDefault,
-      const int max,
-      const int min = 0) override;
-   wxSpinCtrl * TieSpinCtrl(
-      const wxString &Prompt,
-      const wxString &SettingName,
-      const int Value,
-      const int max,
-      const int min) override;
-};
-
 #endif
diff --git a/src/Tags.h b/src/Tags.h
index cc032519f..9955799bf 100644
--- a/src/Tags.h
+++ b/src/Tags.h
@@ -39,6 +39,7 @@
 #include "widgets/wxPanelWrapper.h" // to inherit
 
 #include <unordered_map>
+#include "audacity/Types.h"
 
 class wxArrayString;
 class wxComboBox;
diff --git a/src/UndoManager.cpp b/src/UndoManager.cpp
index 6797d3c2d..379ee8aaa 100644
--- a/src/UndoManager.cpp
+++ b/src/UndoManager.cpp
@@ -78,18 +78,18 @@ UndoManager::~UndoManager()
 
 namespace {
    SpaceArray::value_type
-   CalculateUsage(TrackList *tracks, Set *seen)
+   CalculateUsage(const TrackList &tracks, Set *seen)
    {
       SpaceArray::value_type result = 0;
 
       //TIMER_START( "CalculateSpaceUsage", space_calc );
-      for (auto wt : tracks->Any< WaveTrack >())
+      for (auto wt : tracks.Any< const WaveTrack >())
       {
          // Scan all clips within current track
          for(const auto &clip : wt->GetAllClips())
          {
             // Scan all blockfiles within current clip
-            BlockArray *blocks = clip->GetSequenceBlockArray();
+            auto blocks = clip->GetSequenceBlockArray();
             for (const auto &block : *blocks)
             {
                const auto &file = block.f;
@@ -137,12 +137,12 @@ void UndoManager::CalculateSpaceUsage()
    for (size_t nn = stack.size(); nn--;)
    {
       // Scan all tracks at current level
-      auto tracks = stack[nn]->state.tracks.get();
+      auto &tracks = *stack[nn]->state.tracks;
       space[nn] = CalculateUsage(tracks, &seen);
    }
 
-   mClipboardSpaceUsage = CalculateUsage
-      (AudacityProject::GetClipboardTracks(), nullptr);
+   mClipboardSpaceUsage = CalculateUsage(
+      *AudacityProject::GetClipboardTracks(), nullptr);
 
    //TIMER_STOP( space_calc );
 }
diff --git a/src/WaveClip.cpp b/src/WaveClip.cpp
index de96c02a0..7a1665218 100644
--- a/src/WaveClip.cpp
+++ b/src/WaveClip.cpp
@@ -416,6 +416,11 @@ BlockArray* WaveClip::GetSequenceBlockArray()
    return &mSequence->GetBlockArray();
 }
 
+const BlockArray* WaveClip::GetSequenceBlockArray() const
+{
+   return &mSequence->GetBlockArray();
+}
+
 double WaveClip::GetStartTime() const
 {
    // JS: mOffset is the minimum value and it is returned; no clipping to 0
diff --git a/src/WaveClip.h b/src/WaveClip.h
index 1bdc414c4..b1a2c51d1 100644
--- a/src/WaveClip.h
+++ b/src/WaveClip.h
@@ -238,6 +238,7 @@ public:
    Envelope* GetEnvelope() { return mEnvelope.get(); }
    const Envelope* GetEnvelope() const { return mEnvelope.get(); }
    BlockArray* GetSequenceBlockArray();
+   const BlockArray* GetSequenceBlockArray() const;
 
    // Get low-level access to the sequence. Whenever possible, don't use this,
    // but use more high-level functions inside WaveClip (or add them if you
diff --git a/src/WaveTrack.h b/src/WaveTrack.h
index def340ebe..20720f460 100644
--- a/src/WaveTrack.h
+++ b/src/WaveTrack.h
@@ -374,7 +374,7 @@ private:
    const WaveClipConstHolders &GetClips() const
       { return reinterpret_cast< const WaveClipConstHolders& >( mClips ); }
 
-   // Get access to all clips (in some unspecified sequence),
+   // Get mutative access to all clips (in some unspecified sequence),
    // including those hidden in cutlines.
    class AllClipsIterator
       : public ValueIterator< WaveClip * >
@@ -400,12 +400,12 @@ private:
       AllClipsIterator &operator ++ ();
 
       // Define == well enough to serve for loop termination test
-      friend bool operator ==
-         (const AllClipsIterator &a, const AllClipsIterator &b)
+      friend bool operator == (
+         const AllClipsIterator &a, const AllClipsIterator &b)
       { return a.mStack.empty() == b.mStack.empty(); }
 
-      friend bool operator !=
-         (const AllClipsIterator &a, const AllClipsIterator &b)
+      friend bool operator != (
+         const AllClipsIterator &a, const AllClipsIterator &b)
       { return !( a == b ); }
 
    private:
@@ -419,11 +419,49 @@ private:
       Stack mStack;
    };
 
+   // Get const access to all clips (in some unspecified sequence),
+   // including those hidden in cutlines.
+   class AllClipsConstIterator
+      : public ValueIterator< const WaveClip * >
+   {
+   public:
+      // Constructs an "end" iterator
+      AllClipsConstIterator () {}
+
+      // Construct a "begin" iterator
+      explicit AllClipsConstIterator( const WaveTrack &track )
+         : mIter{ const_cast< WaveTrack& >( track ) }
+      {}
+
+      const WaveClip *operator * () const
+      { return *mIter; }
+
+      AllClipsConstIterator &operator ++ ()
+      { ++mIter; return *this; }
+
+      // Define == well enough to serve for loop termination test
+      friend bool operator == (
+         const AllClipsConstIterator &a, const AllClipsConstIterator &b)
+      { return a.mIter == b.mIter; }
+
+      friend bool operator != (
+         const AllClipsConstIterator &a, const AllClipsConstIterator &b)
+      { return !( a == b ); }
+
+   private:
+      AllClipsIterator mIter;
+   };
+
    IteratorRange< AllClipsIterator > GetAllClips()
    {
       return { AllClipsIterator{ *this }, AllClipsIterator{ } };
    }
-
+   
+   IteratorRange< AllClipsConstIterator > GetAllClips() const
+   {
+      return { AllClipsConstIterator{ *this }, AllClipsConstIterator{ } };
+   }
+   
    // Create NEW clip and add it to this track. Returns a pointer
    // to the newly created clip.
    WaveClip* CreateClip();
diff --git a/src/commands/CommandManager.cpp b/src/commands/CommandManager.cpp
index c54fe8e99..2a4f11902 100644
--- a/src/commands/CommandManager.cpp
+++ b/src/commands/CommandManager.cpp
@@ -1555,9 +1555,8 @@ bool CommandManager::HandleMenuID(int id, CommandFlag flags, CommandMask mask)
 #ifdef EXPERIMENTAL_EASY_CHANGE_KEY_BINDINGS
    if (::wxGetMouseState().ShiftDown()) {
       // Only want one page of the preferences
-      KeyConfigPrefsFactory keyConfigPrefsFactory{ entry->name };
       PrefsDialog::Factories factories;
-      factories.push_back(&keyConfigPrefsFactory);
+      factories.push_back(KeyConfigPrefsFactory( entry->name ));
       GlobalPrefsDialog dialog(GetActiveProject(), factories);
       dialog.ShowModal();
       MenuCreator::RebuildAllMenuBars();
diff --git a/src/commands/GetInfoCommand.cpp b/src/commands/GetInfoCommand.cpp
index ad8b4bfd1..dbab20b7c 100644
--- a/src/commands/GetInfoCommand.cpp
+++ b/src/commands/GetInfoCommand.cpp
@@ -185,6 +185,237 @@ bool GetInfoCommand::SendMenus(const CommandContext &context)
    return true;
 }
 
+namespace {
+
+/**************************************************************************//**
+\brief Shuttle that retrieves a JSON format definition of a command's parameters.
+********************************************************************************/
+class ShuttleGuiGetDefinition : public ShuttleGui, public CommandMessageTargetDecorator
+{
+public:
+   ShuttleGuiGetDefinition(wxWindow * pParent,CommandMessageTarget & target );
+   virtual ~ShuttleGuiGetDefinition();
+
+   wxCheckBox * TieCheckBox(
+      const wxString &Prompt,
+      const wxString &SettingName,
+      const bool bDefault) override;
+   wxCheckBox * TieCheckBoxOnRight(
+      const wxString &Prompt,
+      const wxString &SettingName,
+      const bool bDefault) override;
+   wxChoice * TieChoice(
+      const wxString &Prompt,
+      const wxString &SettingName,
+      const wxString &Default,
+      const wxArrayStringEx &Choices,
+      const wxArrayStringEx & InternalChoices ) override;
+
+   // An assertion will be violated if this override is reached!
+   wxChoice * TieChoice(
+      const wxString &Prompt,
+      const wxString &SettingName,
+      const int Default,
+      const wxArrayStringEx & Choices,
+      const std::vector<int> & InternalChoices) override;
+
+   wxChoice * TieNumberAsChoice(
+      const wxString &Prompt,
+      const wxString &SettingName,
+      const int Default,
+      const wxArrayStringEx & Choices,
+      const std::vector<int> & InternalChoices) override;
+
+   wxTextCtrl * TieTextBox(
+      const wxString &Prompt,
+      const wxString &SettingName,
+      const wxString &Default,
+      const int nChars) override;
+   wxTextCtrl * TieNumericTextBox(
+      const wxString & Prompt,
+      const wxString & SettingName,
+      const double & Default,
+      const int nChars) override;
+   wxSlider * TieSlider(
+      const wxString & Prompt,
+      const wxString & SettingName,
+      const int iDefault,
+      const int max,
+      const int min = 0) override;
+   wxSpinCtrl * TieSpinCtrl(
+      const wxString &Prompt,
+      const wxString &SettingName,
+      const int Value,
+      const int max,
+      const int min) override;
+};
+
+ShuttleGuiGetDefinition::ShuttleGuiGetDefinition(
+   wxWindow * pParent,CommandMessageTarget & target )
+: ShuttleGui( pParent, eIsGettingMetadata ),
+  CommandMessageTargetDecorator( target )
+{
+
+}
+ShuttleGuiGetDefinition::~ShuttleGuiGetDefinition(void)
+{
+}
+
+wxCheckBox * ShuttleGuiGetDefinition::TieCheckBox(
+   const wxString &Prompt,
+   const wxString &SettingName,
+   const bool bDefault) 
+{ 
+   StartStruct();
+   AddItem( SettingName, "id" );
+   AddItem( Prompt, "prompt" );
+   AddItem( "bool", "type" );
+   AddBool( bDefault, "default"  );
+   EndStruct();
+   return ShuttleGui::TieCheckBox( Prompt, SettingName, bDefault );
+}
+wxCheckBox * ShuttleGuiGetDefinition::TieCheckBoxOnRight(
+   const wxString &Prompt,
+   const wxString &SettingName,
+   const bool bDefault) 
+{
+   StartStruct();
+   AddItem( SettingName, "id" );
+   AddItem( Prompt, "prompt" );
+   AddItem( "bool", "type" );
+   AddBool( bDefault, "default"  );
+   EndStruct();
+   return ShuttleGui::TieCheckBoxOnRight( Prompt, SettingName, bDefault );
+}
+wxChoice * ShuttleGuiGetDefinition::TieChoice(
+   const wxString &Prompt,
+   const wxString &SettingName,
+   const wxString &Default,
+   const wxArrayStringEx &Choices,
+   const wxArrayStringEx & InternalChoices )
+{
+   StartStruct();
+   AddItem( SettingName, "id" );
+   AddItem( Prompt, "prompt" );
+   AddItem( "enum", "type" );
+   AddItem( Default, "default"  );
+   StartField( "enum" );
+   StartArray();
+   for( size_t i=0;i<Choices.size(); i++ )
+      AddItem( InternalChoices[i] );
+   EndArray();
+   EndField();
+   EndStruct();
+   return ShuttleGui::TieChoice( Prompt, SettingName, Default, Choices, InternalChoices );
+}
+wxChoice * ShuttleGuiGetDefinition::TieChoice(
+   const wxString &Prompt,
+   const wxString &SettingName,
+   const int Default,
+   const wxArrayStringEx & Choices,
+   const std::vector<int> & InternalChoices)
+{
+   // Should no longer come here!
+   // Choice controls in Preferences that really are exhaustive choices among
+   // non-numerical options must now encode the internal choices as strings,
+   // not numbers.
+   wxASSERT(false);
+
+   // But if we do get here anyway, proceed sub-optimally as before.
+   StartStruct();
+   AddItem( SettingName, "id" );
+   AddItem( Prompt, "prompt" );
+   AddItem( "enum", "type" );
+   AddItem( Default, "default"  );
+   StartField( "enum" );
+   StartArray();
+   for( size_t i=0;i<Choices.size(); i++ )
+      AddItem( Choices[i] );
+   EndArray();
+   EndField();
+   EndStruct();
+   return ShuttleGui::TieChoice( Prompt, SettingName, Default, Choices, InternalChoices );
+}
+wxChoice * ShuttleGuiGetDefinition::TieNumberAsChoice(
+   const wxString &Prompt,
+   const wxString &SettingName,
+   const int Default,
+   const wxArrayStringEx & Choices,
+   const std::vector<int> & InternalChoices)
+{
+   // Come here for controls that present non-exhaustive choices among some
+   //  numbers, with an associated control that allows arbitrary entry of an
+   // "Other..."
+   StartStruct();
+   AddItem( SettingName, "id" );
+   AddItem( Prompt, "prompt" );
+   AddItem( "number", "type" ); // not "enum" !
+   AddItem( Default, "default"  );
+   EndStruct();
+   return ShuttleGui::TieNumberAsChoice(
+      Prompt, SettingName, Default, Choices, InternalChoices );
+}
+wxTextCtrl * ShuttleGuiGetDefinition::TieTextBox(
+   const wxString &Prompt,
+   const wxString &SettingName,
+   const wxString &Default,
+   const int nChars) 
+{
+   StartStruct();
+   AddItem( SettingName, "id" );
+   AddItem( Prompt, "prompt" );
+   AddItem( "string", "type" );
+   AddItem( Default, "default"  );
+   EndStruct();
+   return ShuttleGui::TieTextBox( Prompt, SettingName, Default, nChars );
+}
+wxTextCtrl * ShuttleGuiGetDefinition::TieNumericTextBox(
+   const wxString & Prompt,
+   const wxString & SettingName,
+   const double & Default,
+   const int nChars) 
+{
+   StartStruct();
+   AddItem( SettingName, "id" );
+   AddItem( Prompt, "prompt" );
+   AddItem( "number", "type" );
+   AddItem( Default, "default"  );
+   EndStruct();
+   return ShuttleGui::TieNumericTextBox( Prompt, SettingName, Default, nChars );
+}
+wxSlider * ShuttleGuiGetDefinition::TieSlider(
+   const wxString & Prompt,
+   const wxString & SettingName,
+   const int iDefault,
+   const int max,
+   const int min) 
+{
+   StartStruct();
+   AddItem( SettingName, "id" );
+   AddItem( Prompt, "prompt" );
+   AddItem( "number", "type" );
+   AddItem( iDefault, "default"  );
+   EndStruct();
+   return ShuttleGui::TieSlider( Prompt, SettingName, iDefault, max, min );
+}
+wxSpinCtrl * ShuttleGuiGetDefinition::TieSpinCtrl(
+   const wxString &Prompt,
+   const wxString &SettingName,
+   const int Value,
+   const int max,
+   const int min) 
+{
+   StartStruct();
+   AddItem( SettingName, "id" );
+   AddItem( Prompt, "prompt" );
+   AddItem( "number", "type" );
+   AddItem( Value, "default"  );
+   EndStruct();
+   return ShuttleGui::TieSpinCtrl( Prompt, SettingName, Value, max, min );
+}
+
+}
+
 bool GetInfoCommand::SendPreferences(const CommandContext &context)
 {
    context.StartArray();
diff --git a/src/commands/LoadCommands.cpp b/src/commands/LoadCommands.cpp
index 783b7bd1d..b4f237eda 100644
--- a/src/commands/LoadCommands.cpp
+++ b/src/commands/LoadCommands.cpp
@@ -228,6 +228,12 @@ void BuiltinCommandsModule::Terminate()
    return;
 }
 
+const FileExtensions &BuiltinCommandsModule::GetFileExtensions()
+{
+   static FileExtensions empty;
+   return empty;
+}
+
 bool BuiltinCommandsModule::AutoRegisterPlugins(PluginManagerInterface & pm)
 {
    wxString ignoredErrMsg;
diff --git a/src/commands/LoadCommands.h b/src/commands/LoadCommands.h
index c46a14c58..7a3811d76 100644
--- a/src/commands/LoadCommands.h
+++ b/src/commands/LoadCommands.h
@@ -40,7 +40,7 @@ public:
    bool Initialize() override;
    void Terminate() override;
 
-   FileExtensions GetFileExtensions() override { return {}; }
+   const FileExtensions &GetFileExtensions() override;
    FilePath InstallPath() override { return {}; }
 
    bool AutoRegisterPlugins(PluginManagerInterface & pm) override;
diff --git a/src/effects/LoadEffects.cpp b/src/effects/LoadEffects.cpp
index 4b8b94749..6594b54d5 100644
--- a/src/effects/LoadEffects.cpp
+++ b/src/effects/LoadEffects.cpp
@@ -293,6 +293,12 @@ void BuiltinEffectsModule::Terminate()
    return;
 }
 
+const FileExtensions &BuiltinEffectsModule::GetFileExtensions()
+{
+   static FileExtensions empty;
+   return empty;
+}
+
 bool BuiltinEffectsModule::AutoRegisterPlugins(PluginManagerInterface & pm)
 {
    wxString ignoredErrMsg;
diff --git a/src/effects/LoadEffects.h b/src/effects/LoadEffects.h
index 4ca3157d6..a1cf30d25 100644
--- a/src/effects/LoadEffects.h
+++ b/src/effects/LoadEffects.h
@@ -39,7 +39,7 @@ public:
    bool Initialize() override;
    void Terminate() override;
 
-   FileExtensions GetFileExtensions() override { return {}; }
+   const FileExtensions &GetFileExtensions() override;
    FilePath InstallPath() override { return {}; }
 
    bool AutoRegisterPlugins(PluginManagerInterface & pm) override;
diff --git a/src/effects/VST/VSTEffect.cpp b/src/effects/VST/VSTEffect.cpp
index fec818fda..2e9b64c29 100644
--- a/src/effects/VST/VSTEffect.cpp
+++ b/src/effects/VST/VSTEffect.cpp
@@ -370,9 +370,10 @@ void VSTEffectsModule::Terminate()
    return;
 }
 
-FileExtensions VSTEffectsModule::GetFileExtensions()
+const FileExtensions &VSTEffectsModule::GetFileExtensions()
 {
-   return {{ _T("vst") }};
+   static FileExtensions result{{ _T("vst") }};
+   return result;
 }
 
 FilePath VSTEffectsModule::InstallPath()
diff --git a/src/effects/VST/VSTEffect.h b/src/effects/VST/VSTEffect.h
index edc9277be..64ac039a1 100644
--- a/src/effects/VST/VSTEffect.h
+++ b/src/effects/VST/VSTEffect.h
@@ -416,7 +416,7 @@ public:
    bool Initialize() override;
    void Terminate() override;
 
-   FileExtensions GetFileExtensions() override;
+   const FileExtensions &GetFileExtensions() override;
    FilePath InstallPath() override;
 
    bool AutoRegisterPlugins(PluginManagerInterface & pm) override;
diff --git a/src/effects/audiounits/AudioUnitEffect.cpp b/src/effects/audiounits/AudioUnitEffect.cpp
index e189d7a98..a2ffadd3a 100644
--- a/src/effects/audiounits/AudioUnitEffect.cpp
+++ b/src/effects/audiounits/AudioUnitEffect.cpp
@@ -137,9 +137,10 @@ wxString AudioUnitEffectsModule::GetDescription()
 // ModuleInterface implementation
 // ============================================================================
 
-FileExtensions AudioUnitEffectsModule::GetFileExtensions()
+const FileExtensions &AudioUnitEffectsModule::GetFileExtensions()
 {
-   return {{ _T("au") }};
+   static FileExtensions result{{ _T("au") }};
+   return result;
 }
 
 bool AudioUnitEffectsModule::Initialize()
diff --git a/src/effects/audiounits/AudioUnitEffect.h b/src/effects/audiounits/AudioUnitEffect.h
index df7888170..06ddd0279 100644
--- a/src/effects/audiounits/AudioUnitEffect.h
+++ b/src/effects/audiounits/AudioUnitEffect.h
@@ -241,7 +241,7 @@ public:
    bool Initialize() override;
    void Terminate() override;
 
-   FileExtensions GetFileExtensions() override;
+   const FileExtensions &GetFileExtensions() override;
    FilePath InstallPath() override { return {}; }
 
    bool AutoRegisterPlugins(PluginManagerInterface & pm) override;
diff --git a/src/effects/ladspa/LadspaEffect.cpp b/src/effects/ladspa/LadspaEffect.cpp
index 78d8b1b0b..86a31987c 100644
--- a/src/effects/ladspa/LadspaEffect.cpp
+++ b/src/effects/ladspa/LadspaEffect.cpp
@@ -156,9 +156,9 @@ void LadspaEffectsModule::Terminate()
    return;
 }
 
-FileExtensions LadspaEffectsModule::GetFileExtensions()
+const FileExtensions &LadspaEffectsModule::GetFileExtensions()
 {
-   return {{
+   static FileExtensions result{{
 
 #ifdef __WXMSW__
 
@@ -176,6 +176,7 @@ FileExtensions LadspaEffectsModule::GetFileExtensions()
 #endif
 
    }};
+   return result;
 }
 
 FilePath LadspaEffectsModule::InstallPath()
diff --git a/src/effects/ladspa/LadspaEffect.h b/src/effects/ladspa/LadspaEffect.h
index af8d94647..68a70ca30 100644
--- a/src/effects/ladspa/LadspaEffect.h
+++ b/src/effects/ladspa/LadspaEffect.h
@@ -222,7 +222,7 @@ public:
    bool Initialize() override;
    void Terminate() override;
 
-   FileExtensions GetFileExtensions() override;
+   const FileExtensions &GetFileExtensions() override;
    FilePath InstallPath() override;
 
    bool AutoRegisterPlugins(PluginManagerInterface & pm) override;
diff --git a/src/effects/lv2/LoadLV2.cpp b/src/effects/lv2/LoadLV2.cpp
index 8363eadf2..ea335c9ab 100644
--- a/src/effects/lv2/LoadLV2.cpp
+++ b/src/effects/lv2/LoadLV2.cpp
@@ -207,6 +207,12 @@ void LV2EffectsModule::Terminate()
    return;
 }
 
+const FileExtensions &LV2EffectsModule::GetFileExtensions()
+{
+   static FileExtensions empty;
+   return empty;
+}
+
 bool LV2EffectsModule::AutoRegisterPlugins(PluginManagerInterface & WXUNUSED(pm))
 {
    return false;
diff --git a/src/effects/lv2/LoadLV2.h b/src/effects/lv2/LoadLV2.h
index 491a3f2f6..8f07e06d4 100644
--- a/src/effects/lv2/LoadLV2.h
+++ b/src/effects/lv2/LoadLV2.h
@@ -86,7 +86,7 @@ public:
    bool Initialize() override;
    void Terminate() override;
 
-   FileExtensions GetFileExtensions() override { return {}; }
+   const FileExtensions &GetFileExtensions() override;
    FilePath InstallPath() override { return {}; }
 
    bool AutoRegisterPlugins(PluginManagerInterface & pm) override;
diff --git a/src/effects/nyquist/LoadNyquist.cpp b/src/effects/nyquist/LoadNyquist.cpp
index 55488bfda..16bf8e849 100644
--- a/src/effects/nyquist/LoadNyquist.cpp
+++ b/src/effects/nyquist/LoadNyquist.cpp
@@ -156,9 +156,10 @@ void NyquistEffectsModule::Terminate()
    return;
 }
 
-FileExtensions NyquistEffectsModule::GetFileExtensions()
+const FileExtensions &NyquistEffectsModule::GetFileExtensions()
 {
-   return {{ _T("ny") }};
+   static FileExtensions result{{ _T("ny") }};
+   return result;
 }
 
 FilePath NyquistEffectsModule::InstallPath()
diff --git a/src/effects/nyquist/LoadNyquist.h b/src/effects/nyquist/LoadNyquist.h
index fc0ad49c0..f11b0ec7c 100644
--- a/src/effects/nyquist/LoadNyquist.h
+++ b/src/effects/nyquist/LoadNyquist.h
@@ -37,7 +37,7 @@ public:
    bool Initialize() override;
    void Terminate() override;
 
-   FileExtensions GetFileExtensions() override;
+   const FileExtensions &GetFileExtensions() override;
    FilePath InstallPath() override;
 
    bool AutoRegisterPlugins(PluginManagerInterface & pm) override;
diff --git a/src/effects/vamp/LoadVamp.cpp b/src/effects/vamp/LoadVamp.cpp
index 1f5b41d3f..43dece7d5 100644
--- a/src/effects/vamp/LoadVamp.cpp
+++ b/src/effects/vamp/LoadVamp.cpp
@@ -112,9 +112,10 @@ void VampEffectsModule::Terminate()
    return;
 }
 
-FileExtensions VampEffectsModule::GetFileExtensions()
+const FileExtensions &VampEffectsModule::GetFileExtensions()
 {
-   return {};
+   static FileExtensions empty;
+   return empty;
 }
 
 bool VampEffectsModule::AutoRegisterPlugins(PluginManagerInterface & WXUNUSED(pm))
diff --git a/src/effects/vamp/LoadVamp.h b/src/effects/vamp/LoadVamp.h
index 7c4eb9e3d..23a18cc29 100644
--- a/src/effects/vamp/LoadVamp.h
+++ b/src/effects/vamp/LoadVamp.h
@@ -45,7 +45,7 @@ public:
    bool Initialize() override;
    void Terminate() override;
 
-   FileExtensions GetFileExtensions() override;
+   const FileExtensions &GetFileExtensions() override;
    FilePath InstallPath() override { return {}; }
 
    bool AutoRegisterPlugins(PluginManagerInterface & pm) override;
diff --git a/src/export/ExportFFmpegDialogs.h b/src/export/ExportFFmpegDialogs.h
index e1558cb51..26c2436c6 100644
--- a/src/export/ExportFFmpegDialogs.h
+++ b/src/export/ExportFFmpegDialogs.h
@@ -21,6 +21,7 @@ LRN
 #include "../FileNames.h"
 
 #include <unordered_map>
+#include "audacity/Types.h"
 
 class wxArrayStringEx;
 
diff --git a/src/prefs/BatchPrefs.cpp b/src/prefs/BatchPrefs.cpp
index a1f4e1f69..e6d599377 100644
--- a/src/prefs/BatchPrefs.cpp
+++ b/src/prefs/BatchPrefs.cpp
@@ -95,8 +95,9 @@ BatchPrefs::~BatchPrefs()
 {
 }
 
-PrefsPanel *BatchPrefsFactory::operator () (wxWindow *parent, wxWindowID winid)
+PrefsPanel::Factory
+BatchPrefsFactory = [](wxWindow *parent, wxWindowID winid)
 {
    wxASSERT(parent); // to justify safenew
    return safenew BatchPrefs(parent, winid);
-}
+};
diff --git a/src/prefs/BatchPrefs.h b/src/prefs/BatchPrefs.h
index e5ff5eb7e..49d5d000f 100644
--- a/src/prefs/BatchPrefs.h
+++ b/src/prefs/BatchPrefs.h
@@ -39,10 +39,6 @@ private:
 };
 
 
-/// A PrefsPanelFactory that creates one BatchPrefs panel.
-class BatchPrefsFactory final : public PrefsPanelFactory
-{
-public:
-   PrefsPanel *operator () (wxWindow *parent, wxWindowID winid) override;
-};
+/// A PrefsPanel::Factory that creates one BatchPrefs panel.
+extern PrefsPanel::Factory BatchPrefsFactory;
 #endif
diff --git a/src/prefs/DevicePrefs.cpp b/src/prefs/DevicePrefs.cpp
index da02b6621..1b6d07c01 100644
--- a/src/prefs/DevicePrefs.cpp
+++ b/src/prefs/DevicePrefs.cpp
@@ -420,8 +420,10 @@ bool DevicePrefs::Commit()
    return true;
 }
 
-PrefsPanel *DevicePrefsFactory::operator () (wxWindow *parent, wxWindowID winid)
+PrefsPanel::Factory
+DevicePrefsFactory = [](wxWindow *parent, wxWindowID winid)
+
 {
    wxASSERT(parent); // to justify safenew
    return safenew DevicePrefs(parent, winid);
-}
+};
diff --git a/src/prefs/DevicePrefs.h b/src/prefs/DevicePrefs.h
index e51c069f5..6957d07e7 100644
--- a/src/prefs/DevicePrefs.h
+++ b/src/prefs/DevicePrefs.h
@@ -57,11 +57,7 @@ class DevicePrefs final : public PrefsPanel
    DECLARE_EVENT_TABLE()
 };
 
-/// A PrefsPanelFactory that creates one DevicePrefs panel.
-class DevicePrefsFactory final : public PrefsPanelFactory
-{
-public:
-   PrefsPanel *operator () (wxWindow *parent, wxWindowID winid) override;
-};
+/// A PrefsPanel::Factory that creates one DevicePrefs panel.
+extern PrefsPanel::Factory DevicePrefsFactory;
 
 #endif
diff --git a/src/prefs/DirectoriesPrefs.cpp b/src/prefs/DirectoriesPrefs.cpp
index ad8cefb3f..f9713d1d8 100644
--- a/src/prefs/DirectoriesPrefs.cpp
+++ b/src/prefs/DirectoriesPrefs.cpp
@@ -287,8 +287,11 @@ bool DirectoriesPrefs::Commit()
    return true;
 }
 
-PrefsPanel *DirectoriesPrefsFactory::operator () (wxWindow *parent, wxWindowID winid)
-{
-   wxASSERT(parent); // to justify safenew
-   return safenew DirectoriesPrefs(parent, winid);
+PrefsPanel::Factory
+DirectoriesPrefsFactory() {
+   return [](wxWindow *parent, wxWindowID winid)
+   {
+      wxASSERT(parent); // to justify safenew
+      return safenew DirectoriesPrefs(parent, winid);
+   };
 }
diff --git a/src/prefs/DirectoriesPrefs.h b/src/prefs/DirectoriesPrefs.h
index 3dac185c2..bf4681f1f 100644
--- a/src/prefs/DirectoriesPrefs.h
+++ b/src/prefs/DirectoriesPrefs.h
@@ -44,10 +44,7 @@ class DirectoriesPrefs final : public PrefsPanel
    DECLARE_EVENT_TABLE()
 };
 
-/// A PrefsPanelFactory that creates one DirectoriesPrefs panel.
-class DirectoriesPrefsFactory final : public PrefsPanelFactory
-{
-public:
-   PrefsPanel *operator () (wxWindow *parent, wxWindowID winid) override;
-};
+/// A PrefsPanel::Factory that creates one DirectoriesPrefs panel.
+/// This one is used not only in the Preferences command.
+extern PrefsPanel::Factory DirectoriesPrefsFactory();
 #endif
diff --git a/src/prefs/EffectsPrefs.cpp b/src/prefs/EffectsPrefs.cpp
index a5f7721f5..350644ca8 100644
--- a/src/prefs/EffectsPrefs.cpp
+++ b/src/prefs/EffectsPrefs.cpp
@@ -200,8 +200,9 @@ bool EffectsPrefs::Commit()
    return true;
 }
 
-PrefsPanel *EffectsPrefsFactory::operator () (wxWindow *parent, wxWindowID winid)
+PrefsPanel::Factory
+EffectsPrefsFactory = [](wxWindow *parent, wxWindowID winid)
 {
    wxASSERT(parent); // to justify safenew
    return safenew EffectsPrefs(parent, winid);
-}
+};
diff --git a/src/prefs/EffectsPrefs.h b/src/prefs/EffectsPrefs.h
index 3c7b71363..6c5ba3a6d 100644
--- a/src/prefs/EffectsPrefs.h
+++ b/src/prefs/EffectsPrefs.h
@@ -37,10 +37,6 @@ class EffectsPrefs final : public PrefsPanel
    void Populate();
 };
 
-/// A PrefsPanelFactory that creates one EffectsPrefs panel.
-class EffectsPrefsFactory final : public PrefsPanelFactory
-{
-public:
-   PrefsPanel *operator () (wxWindow *parent, wxWindowID winid) override;
-};
+/// A PrefsPanel::Factory that creates one EffectsPrefs panel.
+extern PrefsPanel::Factory EffectsPrefsFactory;
 #endif
diff --git a/src/prefs/ExtImportPrefs.cpp b/src/prefs/ExtImportPrefs.cpp
index aab12e37f..d99855b4d 100644
--- a/src/prefs/ExtImportPrefs.cpp
+++ b/src/prefs/ExtImportPrefs.cpp
@@ -822,8 +822,9 @@ void ExtImportPrefsDropTarget::OnLeave()
 {
 }
 
-PrefsPanel *ExtImportPrefsFactory::operator () (wxWindow *parent, wxWindowID winid)
+PrefsPanel::Factory
+ExtImportPrefsFactory = [](wxWindow *parent, wxWindowID winid)
 {
    wxASSERT(parent); // to justify safenew
    return safenew ExtImportPrefs(parent, winid);
-}
+};
diff --git a/src/prefs/ExtImportPrefs.h b/src/prefs/ExtImportPrefs.h
index 5ded7040f..20b83555f 100644
--- a/src/prefs/ExtImportPrefs.h
+++ b/src/prefs/ExtImportPrefs.h
@@ -114,10 +114,6 @@ class ExtImportPrefs final : public PrefsPanel
 };
 
 
-/// A PrefsPanelFactory that creates one ExtImportPrefs panel.
-class ExtImportPrefsFactory final : public PrefsPanelFactory
-{
-public:
-   PrefsPanel *operator () (wxWindow *parent, wxWindowID winid) override;
-};
+/// A PrefsPanel::Factory that creates one ExtImportPrefs panel.
+extern PrefsPanel::Factory ExtImportPrefsFactory;
 #endif
diff --git a/src/prefs/GUIPrefs.cpp b/src/prefs/GUIPrefs.cpp
index 5b153c371..5c60ab2d8 100644
--- a/src/prefs/GUIPrefs.cpp
+++ b/src/prefs/GUIPrefs.cpp
@@ -268,8 +268,9 @@ bool GUIPrefs::Commit()
    return true;
 }
 
-PrefsPanel *GUIPrefsFactory::operator () (wxWindow *parent, wxWindowID winid)
+PrefsPanel::Factory
+GUIPrefsFactory = [](wxWindow *parent, wxWindowID winid)
 {
    wxASSERT(parent); // to justify safenew
    return safenew GUIPrefs(parent, winid);
-}
+};
diff --git a/src/prefs/GUIPrefs.h b/src/prefs/GUIPrefs.h
index b4dbe48c2..b738289d5 100644
--- a/src/prefs/GUIPrefs.h
+++ b/src/prefs/GUIPrefs.h
@@ -53,10 +53,6 @@ class GUIPrefs final : public PrefsPanel
    wxArrayStringEx mRangeChoices;
 };
 
-/// A PrefsPanelFactory that creates one GUIPrefs panel.
-class GUIPrefsFactory final : public PrefsPanelFactory
-{
-public:
-   PrefsPanel *operator () (wxWindow *parent, wxWindowID winid) override;
-};
+/// A PrefsPanel::Factory that creates one GUIPrefs panel.
+extern PrefsPanel::Factory GUIPrefsFactory;
 #endif
diff --git a/src/prefs/ImportExportPrefs.cpp b/src/prefs/ImportExportPrefs.cpp
index 07a724743..bbf0a5c91 100644
--- a/src/prefs/ImportExportPrefs.cpp
+++ b/src/prefs/ImportExportPrefs.cpp
@@ -128,8 +128,9 @@ bool ImportExportPrefs::Commit()
    return true;
 }
 
-PrefsPanel *ImportExportPrefsFactory::operator () (wxWindow *parent, wxWindowID winid)
+PrefsPanel::Factory
+ImportExportPrefsFactory = [](wxWindow *parent, wxWindowID winid)
 {
    wxASSERT(parent); // to justify safenew
    return safenew ImportExportPrefs(parent, winid);
-}
+};
diff --git a/src/prefs/ImportExportPrefs.h b/src/prefs/ImportExportPrefs.h
index bcdc0f7ac..223c9e2b8 100644
--- a/src/prefs/ImportExportPrefs.h
+++ b/src/prefs/ImportExportPrefs.h
@@ -37,10 +37,6 @@ class ImportExportPrefs final : public PrefsPanel
    void Populate();
 };
 
-/// A PrefsPanelFactory that creates one ImportExportPrefs panel.
-class ImportExportPrefsFactory final : public PrefsPanelFactory
-{
-public:
-   PrefsPanel *operator () (wxWindow *parent, wxWindowID winid) override;
-};
+/// A PrefsPanel::Factory that creates one ImportExportPrefs panel.
+extern PrefsPanel::Factory ImportExportPrefsFactory;
 #endif
diff --git a/src/prefs/KeyConfigPrefs.cpp b/src/prefs/KeyConfigPrefs.cpp
index d687d2089..269b6be4f 100644
--- a/src/prefs/KeyConfigPrefs.cpp
+++ b/src/prefs/KeyConfigPrefs.cpp
@@ -688,9 +688,13 @@ void KeyConfigPrefs::Cancel()
    return;
 }
 
-PrefsPanel *KeyConfigPrefsFactory::operator () (wxWindow *parent, wxWindowID winid)
+PrefsPanel::Factory
+KeyConfigPrefsFactory( const CommandID &name )
 {
-   wxASSERT(parent); // to justify safenew
-   auto result = safenew KeyConfigPrefs{ parent, winid, mName };
-   return result;
+   return [=](wxWindow *parent, wxWindowID winid)
+   {
+      wxASSERT(parent); // to justify safenew
+      auto result = safenew KeyConfigPrefs{ parent, winid, name };
+      return result;
+   };
 }
diff --git a/src/prefs/KeyConfigPrefs.h b/src/prefs/KeyConfigPrefs.h
index 64513e246..8c8e236df 100644
--- a/src/prefs/KeyConfigPrefs.h
+++ b/src/prefs/KeyConfigPrefs.h
@@ -93,15 +93,9 @@ private:
 };
 
 
-/// A PrefsPanelFactory that creates one KeyConfigPrefs panel.
-class KeyConfigPrefsFactory final : public PrefsPanelFactory
-{
-public:
-   KeyConfigPrefsFactory(const CommandID &name = {})
-      : mName{ name } {}
-   PrefsPanel *operator () (wxWindow *parent, wxWindowID winid) override;
-
-private:
-   CommandID mName;
-};
+/// A PrefsPanel::Factory that creates one KeyConfigPrefs panel.
+/// This factory can be parametrized by name, which specifies a command to be
+/// focused initially
+extern PrefsPanel::Factory KeyConfigPrefsFactory(
+   const CommandID &name = {} );
 #endif
diff --git a/src/prefs/LibraryPrefs.cpp b/src/prefs/LibraryPrefs.cpp
index edef7ed55..8f47d3b89 100644
--- a/src/prefs/LibraryPrefs.cpp
+++ b/src/prefs/LibraryPrefs.cpp
@@ -267,8 +267,9 @@ bool LibraryPrefs::Commit()
    return true;
 }
 
-PrefsPanel *LibraryPrefsFactory::operator () (wxWindow *parent, wxWindowID winid)
+PrefsPanel::Factory
+LibraryPrefsFactory = [](wxWindow *parent, wxWindowID winid)
 {
    wxASSERT(parent); // to justify safenew
    return safenew LibraryPrefs(parent, winid);
-}
+};
diff --git a/src/prefs/LibraryPrefs.h b/src/prefs/LibraryPrefs.h
index e90a2f13d..2aa8fa960 100644
--- a/src/prefs/LibraryPrefs.h
+++ b/src/prefs/LibraryPrefs.h
@@ -50,10 +50,6 @@ class LibraryPrefs final : public PrefsPanel
    DECLARE_EVENT_TABLE()
 };
 
-/// A PrefsPanelFactory that creates one LibraryPrefs panel.
-class LibraryPrefsFactory final : public PrefsPanelFactory
-{
-public:
-   PrefsPanel *operator () (wxWindow *parent, wxWindowID winid) override;
-};
+/// A PrefsPanel::Factory that creates one LibraryPrefs panel.
+extern PrefsPanel::Factory LibraryPrefsFactory;
 #endif
diff --git a/src/prefs/MidiIOPrefs.cpp b/src/prefs/MidiIOPrefs.cpp
index 5e2315a2d..43b052e0a 100644
--- a/src/prefs/MidiIOPrefs.cpp
+++ b/src/prefs/MidiIOPrefs.cpp
@@ -299,10 +299,11 @@ bool MidiIOPrefs::Validate()
    return true;
 }
 
-PrefsPanel *MidiIOPrefsFactory::operator () (wxWindow *parent, wxWindowID winid)
+PrefsPanel::Factory
+MidiIOPrefsFactory = [](wxWindow *parent, wxWindowID winid)
 {
    wxASSERT(parent); // to justify safenew
    return safenew MidiIOPrefs(parent, winid);
-}
+};
 
 #endif
diff --git a/src/prefs/MidiIOPrefs.h b/src/prefs/MidiIOPrefs.h
index 51d448ff4..d0627e43f 100644
--- a/src/prefs/MidiIOPrefs.h
+++ b/src/prefs/MidiIOPrefs.h
@@ -68,12 +68,8 @@ class MidiIOPrefs final : public PrefsPanel
    DECLARE_EVENT_TABLE()
 };
 
-/// A PrefsPanelFactory that creates one MidiIOPrefs panel.
-class MidiIOPrefsFactory final : public PrefsPanelFactory
-{
-public:
-   PrefsPanel *operator () (wxWindow *parent, wxWindowID winid) override;
-};
+/// A PrefsPanel::Factory that creates one MidiIOPrefs panel.
+extern PrefsPanel::Factory MidiIOPrefsFactory;
 #endif
 
 #endif
diff --git a/src/prefs/ModulePrefs.cpp b/src/prefs/ModulePrefs.cpp
index ab5c763fc..9b315dbc2 100644
--- a/src/prefs/ModulePrefs.cpp
+++ b/src/prefs/ModulePrefs.cpp
@@ -180,8 +180,9 @@ void ModulePrefs::SetModuleStatus(const FilePath &fname, int iStatus){
    gPrefs->Flush();
 }
 
-PrefsPanel *ModulePrefsFactory::operator () (wxWindow *parent, wxWindowID winid)
+PrefsPanel::Factory
+ModulePrefsFactory = [](wxWindow *parent, wxWindowID winid)
 {
    wxASSERT(parent); // to justify safenew
    return safenew ModulePrefs(parent, winid);
-}
+};
diff --git a/src/prefs/ModulePrefs.h b/src/prefs/ModulePrefs.h
index a20845e93..c99cd3bdd 100644
--- a/src/prefs/ModulePrefs.h
+++ b/src/prefs/ModulePrefs.h
@@ -55,10 +55,6 @@ class ModulePrefs final : public PrefsPanel
    FilePaths mPaths;
 };
 
-/// A PrefsPanelFactory that creates one ModulePrefs panel.
-class ModulePrefsFactory final : public PrefsPanelFactory
-{
-public:
-   PrefsPanel *operator () (wxWindow *parent, wxWindowID winid) override;
-};
+/// A PrefsPanel::Factory that creates one ModulePrefs panel.
+extern PrefsPanel::Factory ModulePrefsFactory;
 #endif
diff --git a/src/prefs/MousePrefs.cpp b/src/prefs/MousePrefs.cpp
index 5eccce472..57fd4ccb6 100644
--- a/src/prefs/MousePrefs.cpp
+++ b/src/prefs/MousePrefs.cpp
@@ -218,8 +218,9 @@ bool MousePrefs::Commit()
    return true;
 }
 
-PrefsPanel *MousePrefsFactory::operator () (wxWindow *parent, wxWindowID winid)
+PrefsPanel::Factory
+MousePrefsFactory = [](wxWindow *parent, wxWindowID winid)
 {
    wxASSERT(parent); // to justify safenew
    return safenew MousePrefs(parent, winid);
-}
+};
diff --git a/src/prefs/MousePrefs.h b/src/prefs/MousePrefs.h
index 318576dfe..1ccf8bd74 100644
--- a/src/prefs/MousePrefs.h
+++ b/src/prefs/MousePrefs.h
@@ -41,10 +41,6 @@ class MousePrefs final : public PrefsPanel
    wxListCtrl * mList;
 };
 
-/// A PrefsPanelFactory that creates one MousePrefs panel.
-class MousePrefsFactory final : public PrefsPanelFactory
-{
-public:
-   PrefsPanel *operator () (wxWindow *parent, wxWindowID winid) override;
-};
+/// A PrefsPanel::Factory that creates one MousePrefs panel.
+extern PrefsPanel::Factory MousePrefsFactory;
 #endif
diff --git a/src/prefs/PlaybackPrefs.cpp b/src/prefs/PlaybackPrefs.cpp
index ab60f9013..9daef6182 100644
--- a/src/prefs/PlaybackPrefs.cpp
+++ b/src/prefs/PlaybackPrefs.cpp
@@ -183,9 +183,10 @@ bool PlaybackPrefs::Commit()
    return true;
 }
 
-PrefsPanel *PlaybackPrefsFactory::operator () (wxWindow *parent, wxWindowID winid)
+PrefsPanel::Factory
+PlaybackPrefsFactory = [](wxWindow *parent, wxWindowID winid)
 {
    wxASSERT(parent); // to justify safenew
    return safenew PlaybackPrefs(parent, winid);
-}
+};
 
diff --git a/src/prefs/PlaybackPrefs.h b/src/prefs/PlaybackPrefs.h
index d36d1e27e..0cc917c74 100644
--- a/src/prefs/PlaybackPrefs.h
+++ b/src/prefs/PlaybackPrefs.h
@@ -39,11 +39,7 @@ class PlaybackPrefs final : public PrefsPanel
 };
 
 
-/// A PrefsPanelFactory that creates one PlaybackPrefs panel.
-class PlaybackPrefsFactory final : public PrefsPanelFactory
-{
-public:
-   PrefsPanel *operator () (wxWindow *parent, wxWindowID winid) override;
-};
+/// A PrefsPanel::Factory that creates one PlaybackPrefs panel.
+extern PrefsPanel::Factory PlaybackPrefsFactory;
 
 #endif
diff --git a/src/prefs/PrefsDialog.cpp b/src/prefs/PrefsDialog.cpp
index a8bf4ca7d..0b1e57ac8 100644
--- a/src/prefs/PrefsDialog.cpp
+++ b/src/prefs/PrefsDialog.cpp
@@ -487,72 +487,42 @@ PrefsDialog::Factories
 {
    // To do, perhaps:  create this table by registration, without including each PrefsPanel
    // class... and thus allowing a plug-in protocol
-   static DevicePrefsFactory devicePrefsFactory;
-   static PlaybackPrefsFactory playbackPrefsFactory;
-   static RecordingPrefsFactory recordingPrefsFactory;
-#ifdef EXPERIMENTAL_MIDI_OUT
-   static MidiIOPrefsFactory midiIOPrefsFactory;
-#endif
-   static QualityPrefsFactory qualityPrefsFactory;
-   static GUIPrefsFactory guiPrefsFactory;
-   static TracksPrefsFactory tracksPrefsFactory;
-   static ImportExportPrefsFactory importExportPrefsFactory;
-   static ExtImportPrefsFactory extImportPrefsFactory;
-   static ProjectsPrefsFactory projectsPrefsFactory;
-#if !defined(DISABLE_DYNAMIC_LOADING_FFMPEG) || !defined(DISABLE_DYNAMIC_LOADING_LAME)
-   static LibraryPrefsFactory libraryPrefsFactory;
-#endif
-   // static WaveformPrefsFactory waveformPrefsFactory;
-   static TracksBehaviorsPrefsFactory tracksBehaviorsPrefsFactory;
-   static SpectrumPrefsFactory spectrumPrefsFactory;
-   static DirectoriesPrefsFactory directoriesPrefsFactory;
-   static WarningsPrefsFactory warningsPrefsFactory;
-   static EffectsPrefsFactory effectsPrefsFactory;
-#ifdef EXPERIMENTAL_THEME_PREFS
-   static ThemePrefsFactory themePrefsFactory;
-#endif
-   // static BatchPrefsFactory batchPrefsFactory;
-   static KeyConfigPrefsFactory keyConfigPrefsFactory;
-   static MousePrefsFactory mousePrefsFactory;
-#ifdef EXPERIMENTAL_MODULE_PREFS
-   static ModulePrefsFactory modulePrefsFactory;
-#endif
 
    static PrefsNode nodes[] = {
-      &devicePrefsFactory,
-      &playbackPrefsFactory,
-      &recordingPrefsFactory,
+      DevicePrefsFactory,
+      PlaybackPrefsFactory,
+      RecordingPrefsFactory,
 #ifdef EXPERIMENTAL_MIDI_OUT
-      &midiIOPrefsFactory,
+      MidiIOPrefsFactory,
 #endif
-      &qualityPrefsFactory,
-      &guiPrefsFactory,
+      QualityPrefsFactory,
+      GUIPrefsFactory,
 
       // Group other page(s)
-      PrefsNode(&tracksPrefsFactory, 2),
-      // &waveformPrefsFactory,
-      &tracksBehaviorsPrefsFactory,
-      &spectrumPrefsFactory,
+      PrefsNode(TracksPrefsFactory, 2),
+      // WaveformPrefsFactory(),
+      TracksBehaviorsPrefsFactory,
+      SpectrumPrefsFactory(),
 
       // Group one other page
-      PrefsNode(&importExportPrefsFactory, 1),
-      &extImportPrefsFactory,
+      PrefsNode(ImportExportPrefsFactory, 1),
+      ExtImportPrefsFactory,
 
-      &projectsPrefsFactory,
+      ProjectsPrefsFactory,
 #if !defined(DISABLE_DYNAMIC_LOADING_FFMPEG) || !defined(DISABLE_DYNAMIC_LOADING_LAME)
-      &libraryPrefsFactory,
+      LibraryPrefsFactory,
 #endif
-      &directoriesPrefsFactory,
-      &warningsPrefsFactory,
-      &effectsPrefsFactory,
+      DirectoriesPrefsFactory(),
+      WarningsPrefsFactory,
+      EffectsPrefsFactory,
 #ifdef EXPERIMENTAL_THEME_PREFS
-      &themePrefsFactory,
+      ThemePrefsFactory,
 #endif
       // &batchPrefsFactory,
-      &keyConfigPrefsFactory,
-      &mousePrefsFactory,
+      KeyConfigPrefsFactory(),
+      MousePrefsFactory,
 #ifdef EXPERIMENTAL_MODULE_PREFS
-      &modulePrefsFactory,
+      ModulePrefsFactory,
 #endif
    };
 
@@ -601,7 +571,7 @@ PrefsDialog::PrefsDialog
                   it != end; ++it, ++iPage)
                {
                   const PrefsNode &node = *it;
-                  PrefsPanelFactory &factory = *node.pFactory;
+                  const PrefsPanel::Factory &factory = node.factory;
                   wxWindow *const w = factory(mCategories, wxID_ANY);
                   if (stack.empty())
                      // Parameters are: AddPage(page, name, IsSelected, imageId).
@@ -629,7 +599,7 @@ PrefsDialog::PrefsDialog
 
          // Unique page, don't show the factory
          const PrefsNode &node = factories[0];
-         PrefsPanelFactory &factory = *node.pFactory;
+         const PrefsPanel::Factory &factory = node.factory;
          mUniquePage = factory(this, wxID_ANY);
          wxWindow * uniquePageWindow = S.Prop(1).AddWindow(mUniquePage, wxEXPAND);
          // We're not in the wxTreebook, so add the accelerator here
diff --git a/src/prefs/PrefsDialog.h b/src/prefs/PrefsDialog.h
index 49942c193..4945ce032 100644
--- a/src/prefs/PrefsDialog.h
+++ b/src/prefs/PrefsDialog.h
@@ -12,6 +12,7 @@
 #ifndef __AUDACITY_PREFS_DIALOG__
 #define __AUDACITY_PREFS_DIALOG__
 
+#include <functional>
 #include <vector>
 #include "../widgets/wxPanelWrapper.h" // to inherit
 #include "../Internat.h"
@@ -19,7 +20,6 @@
 class wxTreebook;
 class wxTreeEvent;
 class PrefsPanel;
-class PrefsPanelFactory;
 class ShuttleGui;
 
 #ifdef __GNUC__
@@ -33,14 +33,16 @@ class PrefsDialog /* not final */ : public wxDialogWrapper
  public:
     // An array of PrefsNode specifies the tree of pages in pre-order traversal.
     struct PrefsNode {
-       PrefsPanelFactory * CONST pFactory;
+       using Factory =
+         std::function< PrefsPanel * (wxWindow *parent, wxWindowID winid) >;
+       Factory factory;
        CONST int nChildren;
        bool expanded;
 
-       PrefsNode(PrefsPanelFactory *pFactory_,
+       PrefsNode(const Factory &factory_,
           int nChildren_ = 0,
           bool expanded_ = true)
-          : pFactory(pFactory_), nChildren(nChildren_), expanded(expanded_)
+          : factory(factory_), nChildren(nChildren_), expanded(expanded_)
        {}
     };
    typedef std::vector<PrefsNode> Factories;
diff --git a/src/prefs/PrefsPanel.h b/src/prefs/PrefsPanel.h
index fc743702f..ccde697de 100644
--- a/src/prefs/PrefsPanel.h
+++ b/src/prefs/PrefsPanel.h
@@ -22,17 +22,12 @@ MousePrefs, QualityPrefs, SpectrumPrefs and ThemePrefs.
   To actually add the new panel, edit the PrefsDialog constructor
   to append the panel to its list of panels.
 
-*******************************************************************//**
-
-\class PrefsPanelFactory
-\brief Base class for factories such as GUIPrefsFactory that produce a
-PrefsPanel.
-
 *//*******************************************************************/
 
 #ifndef __AUDACITY_PREFS_PANEL__
 #define __AUDACITY_PREFS_PANEL__
 
+#include <functional>
 #include "../widgets/wxPanelWrapper.h" // to inherit
 #include "../include/audacity/ComponentInterface.h"
 
@@ -52,6 +47,11 @@ class ShuttleGui;
 class PrefsPanel /* not final */ : public wxPanelWrapper, ComponentInterface
 {
  public:
+   // \brief Type alias for factories such as GUIPrefsFactory that produce a
+   // PrefsPanel.
+   using Factory =
+      std::function< PrefsPanel * (wxWindow *parent, wxWindowID winid) >;
+
    PrefsPanel(wxWindow * parent, wxWindowID winid, const wxString &title)
    :  wxPanelWrapper(parent, winid)
    {
@@ -86,11 +86,4 @@ class PrefsPanel /* not final */ : public wxPanelWrapper, ComponentInterface
    virtual void Cancel();
 };
 
-class PrefsPanelFactory /* not final */
-{
-public:
-   // Precondition: parent != NULL
-   virtual PrefsPanel *operator () (wxWindow *parent, wxWindowID winid) = 0;
-};
-
 #endif
diff --git a/src/prefs/ProjectsPrefs.cpp b/src/prefs/ProjectsPrefs.cpp
index 61f628d20..e379039bd 100644
--- a/src/prefs/ProjectsPrefs.cpp
+++ b/src/prefs/ProjectsPrefs.cpp
@@ -99,8 +99,9 @@ bool ProjectsPrefs::Commit()
    return true;
 }
 
-PrefsPanel *ProjectsPrefsFactory::operator () (wxWindow *parent, wxWindowID winid)
+PrefsPanel::Factory
+ProjectsPrefsFactory = [](wxWindow *parent, wxWindowID winid)
 {
    wxASSERT(parent); // to justify safenew
    return safenew ProjectsPrefs(parent, winid);
-}
+};
diff --git a/src/prefs/ProjectsPrefs.h b/src/prefs/ProjectsPrefs.h
index 6d088d006..d5f23f5c5 100644
--- a/src/prefs/ProjectsPrefs.h
+++ b/src/prefs/ProjectsPrefs.h
@@ -37,10 +37,6 @@ class ProjectsPrefs final : public PrefsPanel
    void Populate();
 };
 
-/// A PrefsPanelFactory that creates one ProjectPrefs panel.
-class ProjectsPrefsFactory final : public PrefsPanelFactory
-{
-public:
-   PrefsPanel *operator () (wxWindow *parent, wxWindowID winid) override;
-};
+/// A PrefsPanel::Factory that creates one ProjectPrefs panel.
+extern PrefsPanel::Factory ProjectsPrefsFactory;
 #endif
diff --git a/src/prefs/QualityPrefs.cpp b/src/prefs/QualityPrefs.cpp
index e8e8f16d6..c3d073bde 100644
--- a/src/prefs/QualityPrefs.cpp
+++ b/src/prefs/QualityPrefs.cpp
@@ -277,11 +277,12 @@ bool QualityPrefs::Commit()
    return true;
 }
 
-PrefsPanel *QualityPrefsFactory::operator () (wxWindow *parent, wxWindowID winid)
+PrefsPanel::Factory
+QualityPrefsFactory = [](wxWindow *parent, wxWindowID winid)
 {
    wxASSERT(parent); // to justify safenew
    return safenew QualityPrefs(parent, winid);
-}
+};
 
 sampleFormat QualityPrefs::SampleFormatChoice()
 {
diff --git a/src/prefs/QualityPrefs.h b/src/prefs/QualityPrefs.h
index b8dc3af92..57ec35707 100644
--- a/src/prefs/QualityPrefs.h
+++ b/src/prefs/QualityPrefs.h
@@ -59,10 +59,6 @@ class QualityPrefs final : public PrefsPanel
    DECLARE_EVENT_TABLE()
 };
 
-/// A PrefsPanelFactory that creates one QualityPrefs panel.
-class QualityPrefsFactory final : public PrefsPanelFactory
-{
-public:
-   PrefsPanel *operator () (wxWindow *parent, wxWindowID winid) override;
-};
+/// A PrefsPanel::Factory that creates one QualityPrefs panel.
+extern PrefsPanel::Factory QualityPrefsFactory;
 #endif
diff --git a/src/prefs/RecordingPrefs.cpp b/src/prefs/RecordingPrefs.cpp
index 643a0b775..7176eb387 100644
--- a/src/prefs/RecordingPrefs.cpp
+++ b/src/prefs/RecordingPrefs.cpp
@@ -305,8 +305,9 @@ void RecordingPrefs::OnToggleCustomName(wxCommandEvent & /* Evt */)
    mToggleCustomName->Enable(mUseCustomTrackName);
 }
 
-PrefsPanel *RecordingPrefsFactory::operator () (wxWindow *parent, wxWindowID winid)
+PrefsPanel::Factory
+RecordingPrefsFactory = [](wxWindow *parent, wxWindowID winid)
 {
    wxASSERT(parent); // to justify safenew
    return safenew RecordingPrefs(parent, winid);
-}
+};
diff --git a/src/prefs/RecordingPrefs.h b/src/prefs/RecordingPrefs.h
index 9349c749a..b39dae7a7 100644
--- a/src/prefs/RecordingPrefs.h
+++ b/src/prefs/RecordingPrefs.h
@@ -44,10 +44,6 @@ class RecordingPrefs final : public PrefsPanel
    DECLARE_EVENT_TABLE()
 };
 
-/// A PrefsPanelFactory that creates one RecordingPrefs panel.
-class RecordingPrefsFactory final : public PrefsPanelFactory
-{
-public:
-   PrefsPanel *operator () (wxWindow *parent, wxWindowID winid) override;
-};
+/// A PrefsPanel::Factory that creates one RecordingPrefs panel.
+extern PrefsPanel::Factory RecordingPrefsFactory;
 #endif
diff --git a/src/prefs/SpectrumPrefs.cpp b/src/prefs/SpectrumPrefs.cpp
index 6d9df4315..3924b08cd 100644
--- a/src/prefs/SpectrumPrefs.cpp
+++ b/src/prefs/SpectrumPrefs.cpp
@@ -575,13 +575,12 @@ BEGIN_EVENT_TABLE(SpectrumPrefs, PrefsPanel)
 
 END_EVENT_TABLE()
 
-SpectrumPrefsFactory::SpectrumPrefsFactory(WaveTrack *wt)
-: mWt(wt)
+PrefsPanel::Factory
+SpectrumPrefsFactory( WaveTrack *wt )
 {
-}
-
-PrefsPanel *SpectrumPrefsFactory::operator () (wxWindow *parent, wxWindowID winid)
-{
-   wxASSERT(parent); // to justify safenew
-   return safenew SpectrumPrefs(parent, winid, mWt);
+   return [=](wxWindow *parent, wxWindowID winid)
+   {
+      wxASSERT(parent); // to justify safenew
+      return safenew SpectrumPrefs(parent, winid, wt);
+   };
 }
diff --git a/src/prefs/SpectrumPrefs.h b/src/prefs/SpectrumPrefs.h
index 2059c766a..fa64c4523 100644
--- a/src/prefs/SpectrumPrefs.h
+++ b/src/prefs/SpectrumPrefs.h
@@ -105,14 +105,8 @@ class SpectrumPrefs final : public PrefsPanel
    bool mCommitted{};
 };
 
-/// A PrefsPanelFactory that creates one SpectrumPrefs panel.
-class SpectrumPrefsFactory final : public PrefsPanelFactory
-{
-public:
-   explicit SpectrumPrefsFactory(WaveTrack *wt = 0);
-   PrefsPanel *operator () (wxWindow *parent, wxWindowID winid) override;
-
-private:
-   WaveTrack *const mWt;
-};
+/// A PrefsPanel::Factory that creates one SpectrumPrefs panel.
+/// This factory can be parametrized by a single track, to change settings
+/// non-globally
+extern PrefsPanel::Factory SpectrumPrefsFactory( WaveTrack *wt = 0 );
 #endif
diff --git a/src/prefs/ThemePrefs.cpp b/src/prefs/ThemePrefs.cpp
index 900ab3f37..47388aaf8 100644
--- a/src/prefs/ThemePrefs.cpp
+++ b/src/prefs/ThemePrefs.cpp
@@ -216,8 +216,9 @@ bool ThemePrefs::Commit()
    return true;
 }
 
-PrefsPanel *ThemePrefsFactory::operator () (wxWindow *parent, wxWindowID winid)
+PrefsPanel::Factory
+ThemePrefsFactory = [](wxWindow *parent, wxWindowID winid)
 {
    wxASSERT(parent); // to justify safenew
    return safenew ThemePrefs(parent, winid);
-}
+};
diff --git a/src/prefs/ThemePrefs.h b/src/prefs/ThemePrefs.h
index d1f6fd938..1e0d24718 100644
--- a/src/prefs/ThemePrefs.h
+++ b/src/prefs/ThemePrefs.h
@@ -46,10 +46,6 @@ class ThemePrefs final : public PrefsPanel
    DECLARE_EVENT_TABLE()
 };
 
-/// A PrefsPanelFactory that creates one ThemePrefs panel.
-class ThemePrefsFactory final : public PrefsPanelFactory
-{
-public:
-   PrefsPanel *operator () (wxWindow *parent, wxWindowID winid) override;
-};
+/// A PrefsPanel::Factory that creates one ThemePrefs panel.
+extern PrefsPanel::Factory ThemePrefsFactory;
 #endif
diff --git a/src/prefs/TracksBehaviorsPrefs.cpp b/src/prefs/TracksBehaviorsPrefs.cpp
index 9655380dc..88ecee536 100644
--- a/src/prefs/TracksBehaviorsPrefs.cpp
+++ b/src/prefs/TracksBehaviorsPrefs.cpp
@@ -134,12 +134,9 @@ bool TracksBehaviorsPrefs::Commit()
    return true;
 }
 
-TracksBehaviorsPrefsFactory::TracksBehaviorsPrefsFactory()
-{
-}
-
-PrefsPanel *TracksBehaviorsPrefsFactory::operator () (wxWindow *parent, wxWindowID winid)
+PrefsPanel::Factory
+TracksBehaviorsPrefsFactory = [](wxWindow *parent, wxWindowID winid)
 {
    wxASSERT(parent); // to justify safenew
    return safenew TracksBehaviorsPrefs(parent, winid);
-}
+};
diff --git a/src/prefs/TracksBehaviorsPrefs.h b/src/prefs/TracksBehaviorsPrefs.h
index f5948a494..7d62e3f5a 100644
--- a/src/prefs/TracksBehaviorsPrefs.h
+++ b/src/prefs/TracksBehaviorsPrefs.h
@@ -43,12 +43,6 @@ class TracksBehaviorsPrefs final : public PrefsPanel
    wxArrayStringEx mSoloChoices;
 };
 
-/// A PrefsPanelFactory that creates one TracksBehaviorsPrefs panel.
-class TracksBehaviorsPrefsFactory final : public PrefsPanelFactory
-{
-public:
-   explicit TracksBehaviorsPrefsFactory();
-   PrefsPanel *operator () (wxWindow *parent, wxWindowID winid) override;
-
-};
+/// A PrefsPanel::Factory that creates one TracksBehaviorsPrefs panel.
+extern PrefsPanel::Factory TracksBehaviorsPrefsFactory;
 #endif
diff --git a/src/prefs/TracksPrefs.cpp b/src/prefs/TracksPrefs.cpp
index e5e9f7c59..f1624f19f 100644
--- a/src/prefs/TracksPrefs.cpp
+++ b/src/prefs/TracksPrefs.cpp
@@ -406,8 +406,9 @@ bool TracksPrefs::Commit()
    return true;
 }
 
-PrefsPanel *TracksPrefsFactory::operator () (wxWindow *parent, wxWindowID winid)
+PrefsPanel::Factory
+TracksPrefsFactory = [](wxWindow *parent, wxWindowID winid)
 {
    wxASSERT(parent); // to justify safenew
    return safenew TracksPrefs(parent, winid);
-}
+};
diff --git a/src/prefs/TracksPrefs.h b/src/prefs/TracksPrefs.h
index 37e4ffe0c..d5c3c1e94 100644
--- a/src/prefs/TracksPrefs.h
+++ b/src/prefs/TracksPrefs.h
@@ -54,10 +54,6 @@ class TracksPrefs final : public PrefsPanel
    static int iPreferencePinned;
 };
 
-/// A PrefsPanelFactory that creates one TracksPrefs panel.
-class TracksPrefsFactory final : public PrefsPanelFactory
-{
-public:
-   PrefsPanel *operator () (wxWindow *parent, wxWindowID winid) override;
-};
+/// A PrefsPanel::Factory that creates one TracksPrefs panel.
+extern PrefsPanel::Factory TracksPrefsFactory;
 #endif
diff --git a/src/prefs/WarningsPrefs.cpp b/src/prefs/WarningsPrefs.cpp
index 5e35603b0..19424d741 100644
--- a/src/prefs/WarningsPrefs.cpp
+++ b/src/prefs/WarningsPrefs.cpp
@@ -106,8 +106,9 @@ bool WarningsPrefs::Commit()
    return true;
 }
 
-PrefsPanel *WarningsPrefsFactory::operator () (wxWindow *parent, wxWindowID winid)
+PrefsPanel::Factory
+WarningsPrefsFactory = [](wxWindow *parent, wxWindowID winid)
 {
    wxASSERT(parent); // to justify safenew
    return safenew WarningsPrefs(parent, winid);
-}
+};
diff --git a/src/prefs/WarningsPrefs.h b/src/prefs/WarningsPrefs.h
index f92223bc3..36e8e402d 100644
--- a/src/prefs/WarningsPrefs.h
+++ b/src/prefs/WarningsPrefs.h
@@ -37,10 +37,6 @@ class WarningsPrefs final : public PrefsPanel
    void PopulateOrExchange(ShuttleGui & S) override;
 };
 
-/// A PrefsPanelFactory that creates one WarningPrefs panel.
-class WarningsPrefsFactory final : public PrefsPanelFactory
-{
-public:
-   PrefsPanel *operator () (wxWindow *parent, wxWindowID winid) override;
-};
+/// A PrefsPanel::Factory that creates one WarningPrefs panel.
+extern PrefsPanel::Factory WarningsPrefsFactory;
 #endif
diff --git a/src/prefs/WaveformPrefs.cpp b/src/prefs/WaveformPrefs.cpp
index 5bd350bde..d5bc0b1e8 100644
--- a/src/prefs/WaveformPrefs.cpp
+++ b/src/prefs/WaveformPrefs.cpp
@@ -247,13 +247,12 @@ EVT_CHOICE(ID_RANGE, WaveformPrefs::OnControl)
 EVT_CHECKBOX(ID_DEFAULTS, WaveformPrefs::OnDefaults)
 END_EVENT_TABLE()
 
-WaveformPrefsFactory::WaveformPrefsFactory(WaveTrack *wt)
-: mWt(wt)
+PrefsPanel::Factory
+WaveformPrefsFactory(WaveTrack *wt)
 {
-}
-
-PrefsPanel *WaveformPrefsFactory::operator () (wxWindow *parent, wxWindowID winid)
-{
-   wxASSERT(parent); // to justify safenew
-   return safenew WaveformPrefs(parent, winid, mWt);
+   return [=](wxWindow *parent, wxWindowID winid)
+   {
+      wxASSERT(parent); // to justify safenew
+      return safenew WaveformPrefs(parent, winid, wt);
+   };
 }
diff --git a/src/prefs/WaveformPrefs.h b/src/prefs/WaveformPrefs.h
index 3f98f0d6b..b79f6122a 100644
--- a/src/prefs/WaveformPrefs.h
+++ b/src/prefs/WaveformPrefs.h
@@ -63,14 +63,8 @@ private:
    bool mPopulating;
 };
 
-/// A PrefsPanelFactory that creates one WaveformPrefs panel.
-class WaveformPrefsFactory final : public PrefsPanelFactory
-{
-public:
-   explicit WaveformPrefsFactory(WaveTrack *wt = 0);
-   PrefsPanel *operator () (wxWindow *parent, wxWindowID winid) override;
-
-private:
-   WaveTrack *const mWt;
-};
+/// A PrefsPanel::Factory that creates one WaveformPrefs panel.
+/// This factory can be parametrized by a single track, to change settings
+/// non-globally
+extern PrefsPanel::Factory WaveformPrefsFactory(WaveTrack *wt);
 #endif
diff --git a/src/tracks/playabletrack/wavetrack/ui/WaveTrackControls.cpp b/src/tracks/playabletrack/wavetrack/ui/WaveTrackControls.cpp
index fc8592d4a..67579d9e1 100644
--- a/src/tracks/playabletrack/wavetrack/ui/WaveTrackControls.cpp
+++ b/src/tracks/playabletrack/wavetrack/ui/WaveTrackControls.cpp
@@ -781,13 +781,10 @@ void WaveTrackMenuTable::OnSpectrogramSettings(wxCommandEvent &)
    }
 
    WaveTrack *const pTrack = static_cast<WaveTrack*>(mpData->pTrack);
-   // WaveformPrefsFactory waveformFactory(pTrack);
-   // TracksBehaviorsPrefsFactory tracksBehaviorsFactory();
-   SpectrumPrefsFactory spectrumFactory(pTrack);
 
    PrefsDialog::Factories factories;
-   // factories.push_back(&waveformFactory);
-   factories.push_back(&spectrumFactory);
+   // factories.push_back(WaveformPrefsFactory( pTrack ));
+   factories.push_back(SpectrumPrefsFactory( pTrack ));
    const int page =
       // (pTrack->GetDisplay() == WaveTrack::Spectrum) ? 1 :
       0;