I recently had a need to
overlay a warning over all the tools I had displayed on a Panel. Basically I wanted a transparent image over
the entire panel that said something like "Warning" over and over
again.
I found some clues on
how to do this at http://stackoverflow.com/questions/4463363/how-can-i-set-the-opacity-or-transparency-of-a-panel-in-winforms
[1]
This guide will be a
complete step by step on how to accomplish this.