Hello, I have been doing some win32 programming using ctypes. I have successfully created windows, common controls, manipulated and shown images, and so forth. However, I am having trouble with custom controls.
I can create a new window class, successfully register it, then successfully create a child window. When the parent window gets the UpdateWindow call, the program crashes. If I set the style of the child to not include WS_VISIBLE, the program does not crash, but the window of course does not appear. If I then call ShowWindow on the child window, the program crashes. I have carefully monitored the windows messages that are being seen by the main window's procedure and the child window's procedure, and the crash always happens right after the first WM_PAINT to the parent window. No further messages are seen by either procedure before it crashes. Before the crash both procedures process normal messages like WM_CREATE etc. Backing up a step, I started from scratch with a main window and a normal child button control, made sure it worked fine, then used SetWindowLong to replace the window procedure on the child control. This works fine as long as I don't replace the window procedure too early - if I replace it before the first call to UpdateWindow in the startup procedure of the application, the program once again crashes (and I really do believe these two problems are related). Basically, it seems that I am missing something vital from my windows procedure that has something to do with the window being a WS_CHILD, and to do with creation or painting. The system's button window procedure has it, and my main window doesn't need it, but my custom child control does. For testing purposes I call DefWindowProc with the appropriate arguments, and don't do anything else in the child window's procedure. Is there something else I need to do though? I'm really stuck, really confused. Any suggestions? -- Henry
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