Hide Drag and Drop Target Box Outline

Does anyone know if it's possible to hide the dashed-line target box surrounding the target area for drag and drop? When someone starts to drag an object, the location is displayed with the box around it and I'd like to use it to test someone's ability without giving them the answer.

Thank you!

falcon's picture

When double clicking the alternatives, the draggables, you edit where it should be possible to drag them. Typically you want to choose all droppables.

When you doubleclick the droppables you choose the solution.

This is not intuitive at all I know, but if you do this the lines will be around all droppables, not only the correct one... :)