C# GlassPane
A hack as WinForms currently does not support glasspane (like Java Swing does).
My idea was to use a System.Windows.Forms.Form with no buttons (minimize, ...), icon or title, with an Opacity level of, let's say, 60%.
Then this GlassPane form is layed on top of the existing window, moving and resizing itself by listening to the following events:
Layout, Move and Closed.
Download the project here (40 kb)