support for optionnally using DirectX for display manipulations

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@20045 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/display.h

@@ -100,6 +100,9 @@ public:
     static int GetFromWindow(wxWindow *window);
 
 
+    // return true if the object was initialized successfully
+    virtual bool IsOk() const { return true; }
+
     // get the display size
     virtual wxRect GetGeometry() const = 0;