Don't overwrite status message when restoring it if it changed.

wxFrameBase::DoGiveHelp() could rewrite the status bar message if it was
changed while the menu was showing.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@61626 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/frame.h

@@ -210,6 +210,9 @@ protected:
 #if wxUSE_STATUSBAR && (wxUSE_MENUS || wxUSE_TOOLBAR)
     // the saved status bar text overwritten by DoGiveHelp()
     wxString m_oldStatusText;
+
+    // the last help string we have shown in the status bar
+    wxString m_lastHelpShown;
 #endif
 
 #if wxUSE_STATUSBAR