Add wxDropSource::SetIcon for wxGTK to mimic SetCursor on the other ports.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@71349 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

interface/wx/dnd.h

@@ -310,10 +310,24 @@ public:
         @param res
             The drag result to set the icon for.
         @param cursor
-            The ion to show when this drag result occurs.
+            The icon to show when this drag result occurs.
+
+        @onlyfor{wxmsw,wxosx}
     */
     void SetCursor(wxDragResult res, const wxCursor& cursor);
 
+    /**
+        Set the icon to use for a certain drag result.
+
+        @param res
+            The drag result to set the icon for.
+        @param icon
+            The icon to show when this drag result occurs.
+
+        @onlyfor{wxgtk}
+    */
+    void SetIcon(wxDragResult res, const wxIcon& icon);
+
     /**
         Sets the data wxDataObject associated with the drop source. This will
         not delete any previously associated data.