Shouldn't you be also checking to make sure that the window handle matches that of the PE window (or whichever child window) that is generating (some of) the messages?
I think I mentioned in an earlier post that I haven't done any work with the windows API. Thanks for clueing me in on the windows handle. It wasn't until you mentioned it that I got to looking at the MSG struct and saw that it gave you the HWND of the window that generated the message. Now I can double check to make sure it was the PE graph that sent the message. Thanks! I had the signal/slot send/receive the HWND as a parameter and then checked it against the HWND of the PE graph in the MainWindow program (CRat) before making any changes. This thread has been a lot of help to me and I hope it helps some one else in the future that has a similar problem getting messages.