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