Added CanApplyParentThemeBackground and use it in wxMSW's

wxNotebook::ApplyThemeBackground.  It's in the common base classes so
that someday it's usage can expand to the other platforms as well.


git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@26085 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/msw/radiobut.h

@@ -52,6 +52,7 @@ public:
     // implementation only from now on
     virtual bool MSWCommand(WXUINT param, WXWORD id);
     virtual void Command(wxCommandEvent& event);
+    virtual bool CanApplyParentThemeBackground() const { return true; }
 
 protected:
     virtual wxSize DoGetBestSize() const;