wxGUI/datacatalog: move or copy location/mapset isn't allowed, show warning message dialog (#822)

gui/wxpython/datacatalog/tree.py

@@ -995,6 +995,18 @@ class DataCatalogTree(TreeView):
     def OnBeginDrag(self, node, event):
         """Just copy necessary data"""
         self.DefineItems(self.GetSelected())
+
+        if self.selected_location and None in self.selected_mapset and \
+           None in self.selected_layer:
+            GMessage(_("Move or copy location isn't allowed"))
+            event.Veto()
+            return
+        elif self.selected_location and self.selected_mapset and \
+             None in self.selected_layer:
+            GMessage(_("Move or copy mapset isn't allowed"))
+            event.Veto()
+            return
+
         if self.selected_layer and not (self._restricted and gisenv()[
                                         'LOCATION_NAME'] != self.selected_location[0].data['name']):
             event.Allow()