handle failure of gtk_drag_begin() (which can happen e.g. because gdk_pointer_grab() failed) in DoDragDrop() (patch 1825237) + minor cleanup in trunk version of the code

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@49608 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/gtk/dnd.h

@@ -80,10 +80,6 @@ public:
     // start drag action
     virtual wxDragResult DoDragDrop(int flags = wxDrag_CopyOnly);
 
-    // GTK implementation
-    void RegisterWindow();
-    void UnregisterWindow();
-
     void PrepareIcon( int action, GdkDragContext *context );
 
     GtkWidget       *m_widget;
@@ -103,6 +99,11 @@ private:
     void SetIcons(const wxIcon& copy,
                   const wxIcon& move,
                   const wxIcon& none);
+
+    // GTK implementation
+    void GTKConnectDragSignals();
+    void GTKDisconnectDragSignals();
+
 };
 
 #endif // _WX_GTK_DND_H_