make wxFrame a wxControlContainer too, so that it behaves in the same way as wxDialog

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@46452 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/frame.h

@@ -190,6 +190,10 @@ protected:
 
     // test whether this window makes part of the frame
     virtual bool IsOneOfBars(const wxWindow *win) const;
+    virtual bool IsClientAreaChild(const wxWindow *child) const
+    {
+        return !IsOneOfBars(child) && wxTopLevelWindow::IsClientAreaChild(child);
+    }
 
 #if wxUSE_MENUS
     // override to update menu bar position when the frame size changes