... instead define new base classes in src/commands that those other
windows can inherit. The classes have nothing but a virtual destructor. This
lets CommandManager use dynamic_cast to detect the special windows.
See commits cbfde23 and 68e4bf6 which added the #include directives
Defaulted move constructors and assignments introduced at 080dd34 are not
essential but might give a bit more efficiency in std::vector on non-Windows.
Previous compilation fix was incorrect! Excpliticly defined move assignments
should not have had no-effect bodies!
I'd changed wxPanelWrapper to wxPanel in investigating bug 1664, and that change mistakenly went through in my 1664 fix.
In the Lyrics window I don't think the wxPanelWrpper's capturing of Tabs is currently necessary, but keeping it means we can add controls to Lyrics Window, and tab between them correctly on Mac, which wxPanelWrapper was introduced to solve.
... Should have no effect on generated code, except perhaps some slight faster
virtual function calls. Mostly useful as documentation of design intent.
Tried to mark every one of our classes that inherits from another, or is a
base for others, or has abstract virtual functions, and a few others besides.
... in the first label track.
Problem was calling wxTextCtrl::AppendText once per label, per push of undo
stack, each call causing event handling.
Now call it only once per push.
