StackOverflow2013

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POHow can I work around the GetParent/EnumChildWindows asymmetry?
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copied!<p>I recently inspect a GUI with Microsoft's Spy++ and noticed a strange structure; it looked like this (warning, ASCII art ahead):</p> <pre> | + 002004D6 "MyRootWindow1" FooClassName | | | + 001F052C "MyChildWindow" ClassOfChildWindow | \ 001D0A8C "MyRootWindow2" SomeOtherClassName </pre> <p>There are two root windows, <code>002004D6</code> and <code>001D0A8c</code>, the former one of which has one child window, <code>001F052C</code>.</p> <p>Now, this would be all good and find if it wasn't for one thing: calling <a href="http://msdn.microsoft.com/en-us/library/ms633510%28VS.85%29.aspx" rel="nofollow noreferrer">GetParent</a> (or watching the 'Parent Window' or 'Owner Window' fields in Spy++) on the child window (<code>001F052C</code>) yields <code>001D0A8C</code>.</p> <p>Read: "MyChildWindow" is a child of "MyRootWindow1", but "MyRootWindow1" is not the parent of "MyChildWindow". Instead, the parent of "MyChildWindow" is "MyRootWindow2" - but, to make this complete, enumerating the children of "MyRootWindow2" does not yield "MyChildWindow".</p> <p>This is a perfectly static GUI applications, so there are no race conditions here or anything.</p> <p>Does anybody know how this can happen? Does anybody know how I can work around this? Until now, I used <a href="http://msdn.microsoft.com/en-us/library/ms633510%28VS.85%29.aspx" rel="nofollow noreferrer">GetParent</a> and <a href="http://msdn.microsoft.com/en-us/library/ms633494%28VS.85%29.aspx" rel="nofollow noreferrer">EnumChildWindows</a> to get the parent (or children) for a given HWND, and I assumed that this relationship is symmetrical. Is there maybe something else I should be using?</p> <p><b>EDIT:</b> Here's the code for a small C++ program which demonstrates the problem:</p> <pre><code>const HINSTANCE thisModule = ::GetModuleHandle( NULL ); HWND oldParent = ::CreateWindow( TEXT("STATIC"), TEXT("Old parent"), WS_VISIBLE | WS_BORDER, 0, 0, 850, 500, NULL, NULL, thisModule, NULL ); HWND child = ::CreateWindow( TEXT("STATIC"), TEXT("This is a sample dialog"), WS_OVERLAPPED | WS_POPUP | WS_VISIBLE | WS_BORDER, 100, 100, 300, 300, oldParent, NULL, thisModule, NULL ); HWND newParent = ::CreateWindow( TEXT("STATIC"), TEXT("Fake main window"), WS_VISIBLE | WS_BORDER, 0, 0, 850, 500, NULL, NULL, thisModule, NULL ); ::SetParent( child, newParent ); </code></pre> <p>Note how the 'child' object has <code>WS_POPUP</code> <em>and</em> <code>WS_OVERLAPPED</code> set, but not <code>WS_CHILD</code>.</p>

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