Hi Rob,

>Does anyone know a way (using a WINAPI call) to make a form's background transparent (ie Backstyle) . There is a way to create a window with this transparent feature (using CreateWindowEX) but can you modify an existing one ?

In theory, yes, by setting a flag in the extended properties of a window. But in practice this will only affect the title bar. Under some circumstances I was able to create a transparent window this way. I think I made it invisible, changed the property and then made it visible again. But in some situations the form was repainted with the gray back ground. So it was not useable in real applications.

Christof