SetWindowLongPtr with DialogBoxParam?

Posted by templatetypedef on Stack Overflow See other posts from Stack Overflow or by templatetypedef
Published on 2011-01-06T06:47:15Z Indexed on 2011/01/06 6:53 UTC
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Hey all-

A while back I was writing a C++ program with the Win32 API that would display a dialog box and then listen to the messages it generated. At one point, I was interested in associating a piece of data with the dialog window. Were I manually creating the window and attaching a window proc, I'd just use SetWindowLongPtr to set the GWLP_USERDATA field to a pointer to the data to associate. However, in this case I was creating and displaying the window with DialogBoxParam, and it wasn't clear whether this function was associating that data with its own internal state. Since the MSDN didn't have a description of what would happen in this case, I ended up using some other approach to solve the problem.

My question is this - is it safe to use SetWindowLongPtr to overwrite the GWLP_USERDATA value in a window created by DialogBoxParam?

Thanks!

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