Added wxFrameBase::OnMenuOpen, and wxUSE_IDLEMENUUPDATES in platform.h

Experimental wxUpdateUIEvent::SetUpdateInterval() function to limit
UI update frequency


git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@21746 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/mgl/window.cpp

@@ -1278,5 +1278,6 @@ wxWindow* wxFindWindowAtPoint(const wxPoint& pt)
 
 void wxWindowMGL::OnIdle(wxIdleEvent& WXUNUSED(event))
 {
-    UpdateWindowUI();
+    if (wxUpdateUIEvent::CanUpdate())
+        UpdateWindowUI();
 }