Reimplement the rejection of select-all-on-none for certain commands...

... Specify it in the menu descriptions.  Don't put special ad hoc logic
in Menus.cpp.

src/commands/CommandManager.cpp

@@ -542,6 +542,7 @@ void CommandManager::AddItem(const CommandID &name,
          hasDialog,
          options.accel, CurrentMenu(), finder, callback,
          {}, 0, 0, options.bIsEffect, cookedParameter);
+   entry->useStrictFlags = options.useStrictFlags;
    int ID = entry->id;
    wxString label = GetLabelWithDisabledAccel(entry);
 
@@ -955,17 +956,26 @@ void CommandManager::Enable(const wxString &name, bool enabled)
    Enable(entry, enabled);
 }
 
-void CommandManager::EnableUsingFlags(CommandFlag flags, CommandMask mask)
+void CommandManager::EnableUsingFlags(
+   CommandFlag flags, CommandFlag strictFlags, CommandMask mask)
 {
+   // strictFlags are a subset of flags.  strictFlags represent the real
+   // conditions now, but flags are the conditions that could be made true.
+   // Some commands use strict flags only, refusing the chance to fix
+   // conditions
+   wxASSERT( (strictFlags & ~flags).none() );
+
    for(const auto &entry : mCommandList) {
       if (entry->multi && entry->index != 0)
          continue;
       if( entry->isOccult )
          continue;
 
+      auto useFlags = entry->useStrictFlags ? strictFlags : flags;
+
       auto combinedMask = (mask & entry->mask);
       if (combinedMask.any()) {
-         bool enable = ((flags & combinedMask) ==
+         bool enable = ((useFlags & combinedMask) ==
                         (entry->flags & combinedMask));
          Enable(entry.get(), enable);
       }

src/commands/CommandManager.h

@@ -82,6 +82,7 @@ struct CommandListEntry
    bool hasDialog;
    CommandFlag flags;
    CommandMask mask;
+   bool useStrictFlags{ false };
 };
 
 using MenuBarList = std::vector < MenuBarListEntry >;
@@ -164,6 +165,8 @@ class AUDACITY_DLL_API CommandManager final
          { longName = value; return std::move(*this); }
       Options &&IsGlobal () &&
          { global = true; return std::move(*this); }
+      Options &&UseStrictFlags () &&
+         { useStrictFlags = true; return std::move(*this); }
 
       const wxChar *accel{ wxT("") };
       int check{ -1 }; // default value means it's not a check item
@@ -172,6 +175,7 @@ class AUDACITY_DLL_API CommandManager final
       CommandMask mask{ NoFlagsSpecified };
       wxString longName{}; // translated
       bool global{ false };
+      bool useStrictFlags{ false };
    };
 
    void AddItemList(const CommandID & name,
@@ -218,7 +222,8 @@ class AUDACITY_DLL_API CommandManager final
    // Modifying menus
    //
 
-   void EnableUsingFlags(CommandFlag flags, CommandMask mask);
+   void EnableUsingFlags(
+      CommandFlag flags, CommandFlag strictFlags, CommandMask mask);
    void Enable(const wxString &name, bool enabled);
    void Check(const CommandID &name, bool checked);
    void Modify(const wxString &name, const wxString &newLabel);