Help: changing the color of the control border when dragging in form.

Believe me: I've been trying for hours:

How do I change the (transparent) color of the control border which
appears when I drag a control across a form in editor mode. It's a very
light grey now, which I can hardly see against the background of the
forms.

I'd be MUCH obliged!

Joris van Dorp

P.S. I'm a university student at the Delft University of Technology. I'm
at your service for info, etc.