The stunner based designers contain "Clear the diagram" button. The problem of this button for DMN Designer appears if the expression editor is opened. User has still possibility to use this button and thus can clear node that he currently edits. I think we should disable that button if expression editor is opened.

Manual acceptance test

Navigate between diagram and expression editor using [1] and check button enabled in diagram, disabled in expression
[1]

• Navigation dock
• Manually clicking elements