diff --git a/src/AdornedRulerPanel.h b/src/AdornedRulerPanel.h
index 77c7dc02f..389b4d26d 100644
--- a/src/AdornedRulerPanel.h
+++ b/src/AdornedRulerPanel.h
@@ -18,7 +18,6 @@
 #include <wx/bitmap.h>
 #include <wx/dc.h>
 #include <wx/dcmemory.h>
-#include <wx/font.h>
 
 class ViewInfo;
 class AudacityProject;
diff --git a/src/AutoRecovery.h b/src/AutoRecovery.h
index b1210a53a..99a8e634a 100644
--- a/src/AutoRecovery.h
+++ b/src/AutoRecovery.h
@@ -15,12 +15,12 @@
 #include "xml/XMLWriter.h"
 
 #include <wx/debug.h>
-#include <wx/ffile.h>
 #include <wx/hashmap.h>
 #include <wx/mstream.h>
 
 #include <unordered_map>
 
+class wxFFile;
 class AudacityProject;
 
 //
diff --git a/src/BlockFile.h b/src/BlockFile.h
index ee0988be5..4f622d1e8 100644
--- a/src/BlockFile.h
+++ b/src/BlockFile.h
@@ -13,7 +13,6 @@
 #define __AUDACITY_BLOCKFILE__
 
 #include "MemoryX.h"
-#include <wx/ffile.h>
 
 #include "xml/XMLTagHandler.h"
 #include "xml/XMLWriter.h"
diff --git a/src/FreqWindow.h b/src/FreqWindow.h
index 908d07dca..005a58b96 100644
--- a/src/FreqWindow.h
+++ b/src/FreqWindow.h
@@ -20,7 +20,7 @@
 #include <wx/dialog.h>
 #include <wx/gdicmn.h>
 #include <wx/pen.h>
-#include <wx/font.h>
+#include <wx/font.h> // member variable
 #include <wx/scrolbar.h>
 #include <wx/statusbr.h>
 #include <wx/utils.h>
diff --git a/src/HistoryWindow.h b/src/HistoryWindow.h
index 7c6d09c41..f700ce77a 100644
--- a/src/HistoryWindow.h
+++ b/src/HistoryWindow.h
@@ -11,12 +11,12 @@
 #ifndef __AUDACITY_HISTORY_WINDOW__
 #define __AUDACITY_HISTORY_WINDOW__
 
-#include <wx/button.h>
 #include <wx/listctrl.h>
 #include <wx/spinctrl.h>
 
 #include "widgets/wxPanelWrapper.h"
 
+class wxButton;
 class wxTextCtrl;
 class AudacityProject;
 class ShuttleGui;
diff --git a/src/ImageManipulation.h b/src/ImageManipulation.h
index 83ca64da4..5475c0d85 100644
--- a/src/ImageManipulation.h
+++ b/src/ImageManipulation.h
@@ -10,9 +10,9 @@
 
 #include "MemoryX.h"
 #include <wx/defs.h>
-#include <wx/colour.h>
 #include "Theme.h"
 
+class wxColour;
 class wxImage;
 
 // This looks at the first pixel in the image, and shifts
diff --git a/src/LabelDialog.h b/src/LabelDialog.h
index c3dac2882..77a0d1250 100644
--- a/src/LabelDialog.h
+++ b/src/LabelDialog.h
@@ -13,13 +13,13 @@
 
 #include <vector>
 #include <wx/defs.h>
-#include <wx/grid.h>
 
 #include "Internat.h"
 #include "widgets/Grid.h"
 #include "widgets/wxPanelWrapper.h"
 
 class wxArrayString;
+class wxGridEvent;
 class TrackFactory;
 class TrackList;
 class RowData;
diff --git a/src/LabelTrack.h b/src/LabelTrack.h
index 78bb1ce38..edda960da 100644
--- a/src/LabelTrack.h
+++ b/src/LabelTrack.h
@@ -17,11 +17,11 @@
 #include "Track.h"
 
 #include <wx/brush.h>
-#include <wx/font.h>
 #include <wx/pen.h>
 #include <wx/clipbrd.h>
 
 
+class wxFont;
 class wxKeyEvent;
 class wxMouseEvent;
 class wxTextFile;
diff --git a/src/MixerBoard.cpp b/src/MixerBoard.cpp
index 2f90452e4..1105ec6fe 100644
--- a/src/MixerBoard.cpp
+++ b/src/MixerBoard.cpp
@@ -21,6 +21,7 @@
 
 #include <wx/setup.h> // for wxUSE_* macros
 
+#include <wx/bmpbuttn.h>
 #include <wx/dcmemory.h>
 #include <wx/icon.h>
 #include <wx/settings.h> // for wxSystemSettings::GetColour and wxSystemSettings::GetMetric
diff --git a/src/MixerBoard.h b/src/MixerBoard.h
index ef860a542..68f1567e0 100644
--- a/src/MixerBoard.h
+++ b/src/MixerBoard.h
@@ -15,7 +15,6 @@
 #define __AUDACITY_MIXER_BOARD__
 
 #include <wx/frame.h> // to inherit
-#include <wx/bmpbuttn.h>
 #include <wx/hashmap.h>
 #include <wx/image.h>
 #include <wx/scrolwin.h>
@@ -27,6 +26,7 @@
 #include "commands/CommandManagerWindowClasses.h"
 
 class wxArrayString;
+class wxBitmapButton;
 struct TrackListEvent;
 
 // containment hierarchy:
diff --git a/src/ShuttleGui.cpp b/src/ShuttleGui.cpp
index 31ceb88db..7ba5e4a2d 100644
--- a/src/ShuttleGui.cpp
+++ b/src/ShuttleGui.cpp
@@ -105,6 +105,7 @@ for registering for changes.
 #include <wx/setup.h> // for wxUSE_* macros
 #include <wx/wx.h>
 #include <wx/wxprec.h>
+#include <wx/grid.h>
 #include <wx/listctrl.h>
 #include <wx/notebook.h>
 #include <wx/treectrl.h>
diff --git a/src/ShuttleGui.h b/src/ShuttleGui.h
index 6b1c7033b..8826493d7 100644
--- a/src/ShuttleGui.h
+++ b/src/ShuttleGui.h
@@ -18,7 +18,6 @@
 
 #include <vector>
 #include "MemoryX.h"
-#include <wx/grid.h>
 
 #include "WrappedType.h"
 
diff --git a/src/Tags.h b/src/Tags.h
index 27f6a93a0..39aa887f9 100644
--- a/src/Tags.h
+++ b/src/Tags.h
@@ -44,7 +44,6 @@
 #include <unordered_map>
 
 class wxArrayString;
-class wxButton;
 class wxComboBox;
 class wxGridCellChoiceEditor;
 class wxRadioButton;
diff --git a/src/Theme.h b/src/Theme.h
index 9c8b5aff0..a4ca5ba39 100644
--- a/src/Theme.h
+++ b/src/Theme.h
@@ -18,13 +18,13 @@
 
 #include <vector>
 #include <wx/bitmap.h>
-#include <wx/colour.h>
 #include <wx/defs.h>
-#include <wx/font.h>
 #include <wx/image.h>
 #include <wx/window.h> // to inherit
 
 class wxArrayString;
+class wxColour;
+class wxFont;
 
 // JKC: will probably change name from 'teBmps' to 'tIndexBmp';
 typedef int teBmps; /// The index of a bitmap resource in Theme Resources.
diff --git a/src/TimerRecordDialog.cpp b/src/TimerRecordDialog.cpp
index 9e7aa8be3..8c1ce9f59 100644
--- a/src/TimerRecordDialog.cpp
+++ b/src/TimerRecordDialog.cpp
@@ -25,6 +25,7 @@
 
 #include <wx/setup.h> // for wxUSE_* macros
 
+#include <wx/button.h>
 #include <wx/choice.h>
 #include <wx/defs.h>
 #include <wx/dir.h>
diff --git a/src/commands/AudacityCommand.h b/src/commands/AudacityCommand.h
index 452d2a4df..7378f05e6 100644
--- a/src/commands/AudacityCommand.h
+++ b/src/commands/AudacityCommand.h
@@ -17,7 +17,6 @@
 #include <set>
 
 #include "../MemoryX.h"
-#include <wx/bmpbuttn.h>
 #include <wx/defs.h>
 #include <wx/dynarray.h>
 #include <wx/intl.h>
diff --git a/src/commands/ScreenshotCommand.h b/src/commands/ScreenshotCommand.h
index 87c996490..4fd327b97 100644
--- a/src/commands/ScreenshotCommand.h
+++ b/src/commands/ScreenshotCommand.h
@@ -16,7 +16,8 @@
 #include "Command.h"
 #include "../commands/AudacityCommand.h"
 
-#include <wx/colour.h>
+#include <wx/colour.h> // member variable
+
 class wxWindow;
 class wxTopLevelWindow;
 class wxCommandEvent;
diff --git a/src/effects/Effect.cpp b/src/effects/Effect.cpp
index 62e5d6562..45dff2311 100644
--- a/src/effects/Effect.cpp
+++ b/src/effects/Effect.cpp
@@ -28,6 +28,7 @@ greater use in future.
 
 #include <algorithm>
 
+#include <wx/bmpbuttn.h>
 #include <wx/checkbox.h>
 #include <wx/choice.h>
 #include <wx/dcmemory.h>
diff --git a/src/effects/Effect.h b/src/effects/Effect.h
index 3dfdb82ce..399c3496b 100644
--- a/src/effects/Effect.h
+++ b/src/effects/Effect.h
@@ -20,11 +20,11 @@
 #include <set>
 
 #include "../MemoryX.h"
-#include <wx/bmpbuttn.h>
 #include <wx/defs.h>
 #include <wx/intl.h>
 #include <wx/tglbtn.h>
 
+class wxButton;
 class wxCheckBox;
 class wxChoice;
 class wxListBox;
diff --git a/src/effects/EffectRack.h b/src/effects/EffectRack.h
index e41d14e08..d1f973301 100644
--- a/src/effects/EffectRack.h
+++ b/src/effects/EffectRack.h
@@ -18,7 +18,6 @@
 
 #if defined(EXPERIMENTAL_EFFECTS_RACK)
 
-#include <wx/bmpbuttn.h>
 #include <wx/defs.h>
 #include <wx/frame.h> // to inherit
 #include <wx/image.h>
diff --git a/src/effects/Equalization.h b/src/effects/Equalization.h
index 5269913cd..a1d9238ce 100644
--- a/src/effects/Equalization.h
+++ b/src/effects/Equalization.h
@@ -17,7 +17,6 @@
 #define NUM_PTS 180
 #define PANELBORDER 1   // only increase from '1' for testing purposes - MJS
 
-#include <wx/button.h>
 #include <wx/setup.h> // for wxUSE_* macros
 #include <wx/panel.h>
 #include <wx/dialog.h>
@@ -52,6 +51,7 @@ const int kEqOptionCurve   =1<<1;
 const int kEqLegacy = kEqOptionGraphic + kEqOptionCurve;
 
 class wxBoxSizer;
+class wxButton;
 class wxChoice;
 class wxSizer;
 class wxSizerItem;
diff --git a/src/effects/nyquist/Nyquist.cpp b/src/effects/nyquist/Nyquist.cpp
index 39bfdeb33..6f3fc40f2 100644
--- a/src/effects/nyquist/Nyquist.cpp
+++ b/src/effects/nyquist/Nyquist.cpp
@@ -34,6 +34,7 @@ effects from this one class.
 
 #include <locale.h>
 
+#include <wx/button.h>
 #include <wx/checkbox.h>
 #include <wx/choice.h>
 #include <wx/datetime.h>
diff --git a/src/effects/nyquist/Nyquist.h b/src/effects/nyquist/Nyquist.h
index ae985d7ae..cbb26cf56 100644
--- a/src/effects/nyquist/Nyquist.h
+++ b/src/effects/nyquist/Nyquist.h
@@ -11,7 +11,6 @@
 #ifndef __AUDACITY_EFFECT_NYQUIST__
 #define __AUDACITY_EFFECT_NYQUIST__
 
-#include <wx/button.h>
 #include <wx/datetime.h>
 #include <wx/dialog.h>
 #include <wx/intl.h>
diff --git a/src/prefs/PrefsDialog.h b/src/prefs/PrefsDialog.h
index 2ea220dd9..17936efd0 100644
--- a/src/prefs/PrefsDialog.h
+++ b/src/prefs/PrefsDialog.h
@@ -13,7 +13,6 @@
 #define __AUDACITY_PREFS_DIALOG__
 
 #include <vector>
-#include <wx/button.h>
 #include <wx/dialog.h>
 #include <wx/treebook.h>
 #include "../widgets/wxPanelWrapper.h"
diff --git a/src/widgets/ASlider.h b/src/widgets/ASlider.h
index e840ea76d..4272f7743 100644
--- a/src/widgets/ASlider.h
+++ b/src/widgets/ASlider.h
@@ -31,7 +31,6 @@ class wxImage;
 class wxSize;
 class wxPoint;
 class wxTextCtrl;
-class wxButton;
 
 class Ruler;
 class TipPanel;
diff --git a/src/widgets/FileHistory.h b/src/widgets/FileHistory.h
index 469da1eab..e1bad424d 100644
--- a/src/widgets/FileHistory.h
+++ b/src/widgets/FileHistory.h
@@ -14,13 +14,13 @@
 #include <vector>
 #include <algorithm>
 #include <wx/defs.h>
-#include <wx/grid.h>
 #include <wx/weakref.h>
 
 #include "audacity/Types.h"
 #include "../MemoryX.h"
 
 class wxConfigBase;
+class wxMenu;
 
 class AUDACITY_DLL_API FileHistory
 {
diff --git a/src/widgets/Grid.h b/src/widgets/Grid.h
index 84a7898ae..87602b37e 100644
--- a/src/widgets/Grid.h
+++ b/src/widgets/Grid.h
@@ -15,7 +15,7 @@
 #include <vector>
 #include <wx/setup.h> // for wxUSE_* macros
 #include <wx/defs.h>
-#include <wx/grid.h>
+#include <wx/grid.h> // to inherit wxGridCellEditor
 #include "NumericTextCtrl.h"
 #include "../Internat.h"
 
diff --git a/src/widgets/HelpSystem.cpp b/src/widgets/HelpSystem.cpp
index 2a77d59a4..fa1149966 100644
--- a/src/widgets/HelpSystem.cpp
+++ b/src/widgets/HelpSystem.cpp
@@ -16,7 +16,7 @@
 #include "../Experimental.h"
 
 #include <wx/setup.h> // for wxUSE_* macros
-#include <wx/button.h>
+#include <wx/bmpbuttn.h>
 #include <wx/icon.h>
 #include <wx/dialog.h>
 #include <wx/intl.h>
diff --git a/src/widgets/Ruler.h b/src/widgets/Ruler.h
index afda69f96..66ca6988d 100644
--- a/src/widgets/Ruler.h
+++ b/src/widgets/Ruler.h
@@ -13,7 +13,7 @@
 
 #include "wxPanelWrapper.h"
 
-#include <wx/colour.h>
+#include <wx/colour.h> // member variable
 #include <wx/gdicmn.h>
 #include <wx/pen.h>
 #include <wx/types.h>
diff --git a/src/xml/XMLWriter.h b/src/xml/XMLWriter.h
index ad9056d27..7e8575177 100644
--- a/src/xml/XMLWriter.h
+++ b/src/xml/XMLWriter.h
@@ -11,7 +11,7 @@
 #define __AUDACITY_XML_XML_FILE_WRITER__
 
 #include <vector>
-#include <wx/ffile.h>
+#include <wx/ffile.h> // to inherit
 
 #include "../FileException.h"