refactor WM_COMMAND messages handling in MDI frames to avoid duplicating code unnecessarily and generally streamline it; added possibility to use custom menu commands in the "Window" menu and specifying accelerators for them now works too (show this in the sample); finally added standard ids for the MDI window menu commands

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@58462 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/msw/frame.h

@@ -107,6 +107,9 @@ public:
     // get the currently active menu: this is the same as the frame menu for
     // normal frames but is overridden by wxMDIParentFrame
     virtual WXHMENU MSWGetActiveMenu() const { return m_hMenu; }
+
+    // find the item in our menu bar: this is again a hook for MDI frames
+    virtual wxMenuItem *MSWFindMenuBarItem(WXWORD id);
 #endif // wxUSE_MENUS
 
 protected: