Fix wxMSW rendering artifacts with modal dialogs.

When a modal dialog showed another modal dialog, parts of the parent
window weren't refreshed correctly. This demonstrated itself as
rendering artifacts when moving the child dialog to another position:
parts of the dialog were shown as disabled, parts as enabled.

Fixed by explicitly refreshing the window.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@65556 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/msw/toplevel.h

@@ -141,6 +141,8 @@ protected:
     virtual void DoFreeze();
     virtual void DoThaw();
 
+    virtual void DoEnable(bool enable);
+
     // helper of SetIcons(): calls gets the icon with the size specified by the
     // given system metrics (SM_C{X|Y}[SM]ICON) from the bundle and sets it
     // using WM_SETICON with the specified wParam (ICOM_SMALL or ICON_BIG);