Dropping an elements on a diagram which is already visible does not give any feedback #1863
Description
Steps to reproduce
- Create an element in a General View diagram.
- Drag & drop the new semantic element from the Explorer View in the General View diagram
The dropped element is already displayed on the diagram, so it is expected that this does not change anything, but there is no user feedback. There should be a user message indicating the dropped element is already visible.
Actually, from the code in DiagramMutationDndService.dropElementFromExplorerInTarget(), it looks like such a message is show in some cases, but not always and not in the basic scenario above.