Handle WM_*MENU* events in wxWindow.

Contrary to MSDN implications, at least some of these messages are not
actually sent to the TLW for popup menus, but to the owning window or
even its parent window (!).

Move the handling of these events from wxTLW to wxWindow.  Move menu
depth tracking to wxFrame, because it only makes sense for frame's
menus and move DoGiveHelp() from wxTLW to wxFrame.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@76721 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/frame.h

@@ -173,7 +173,7 @@ public:
     // show help text for the currently selected menu or toolbar item
     // (typically in the status bar) or hide it and restore the status bar text
     // originally shown before the menu was opened if show == false
-    virtual void DoGiveHelp(const wxString& text, bool show) wxOVERRIDE;
+    virtual void DoGiveHelp(const wxString& text, bool show);
 #endif
 
     virtual bool IsClientAreaChild(const wxWindow *child) const wxOVERRIDE