Hi Laurent,
On the further analysis of the shared detail, we understood that to want the drag and drop support for the drawing tool. The drawing tool functionality would work based on the mouse action, if we enabled a drawing tool and perform the mouse down in diagram, it starts to draw the given node or connector and when we perform the mouse up, the drawing tool get ends so we cannot create the drag and drop support for the drawing tools. We suggest you use the symbol palette for drag and drop a symbol from palette to diagram.
If we misunderstood your requirement, please share with us more details about your requirement or share a video demonstration about your requirement. This will be helpful for us to go ahead further.
Regards,
Gowtham
