use wxEventLoop in wxApp under wxMSW; factored out common code from wxX11/wxMotif/wxMGL to wxAppBase; changed wxApp::Dispatch() return type

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@23609 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/gtk1/app.cpp

@@ -567,9 +567,11 @@ bool wxApp::Pending()
     return (gtk_events_pending() > 0);
 }
 
-void wxApp::Dispatch()
+bool wxApp::Dispatch()
 {
     gtk_main_iteration();
+
+    return true;
 }
 
 bool wxApp::Initialize(int& argc, wxChar **argv)