Knowledge Base

BUG: Opening an AVI file Fails When MCIWnd Is Subclassed

Article ID: 140108

Article Last Modified on 11/3/2003

Microsoft Windows Software Development Kit 3.1
Microsoft Video for Windows Development Kit 1.1

This article was previously published under Q140108

SYMPTOMS

In an application based on Windows 3.1 where an MCIWnd window is subclassed (using SetWindowLong API) and an AVI file is opened by MCIWndOpen macro, if the window is closed (for example, by double-clicking System Menu Box), then no AVI files may be opened in any MCIWnd window created thereafter. Specifically, MCIWndOpen returns MCI error code 289 on subsequent calls.

RESOLUTION

The subclassed window can process a WM_CLOSE message to set the original MCIWnd window procedure back and then forward this message to the original window procedure as in this sample code:

   WM_CLOSE: SetWindowLong(hsubMCIWnd, GWL_WNDPROC, (DWORD)lpfnOldWndProc);
             return CallWindowProc(lpfnOldWndProc, hsubMCIWnd,
             message, wParam, lParam);
            // lpfnOldWndProc points to the original MCIWnd procedure

STATUS

Microsoft has confirmed this to be a bug in the products listed at the beginning of this article. We are researching this problem and will post new information here in the Microsoft Knowledge Base as it becomes available.

Additional query words: 3.10 MCIWndCreate MCI MCIAVI alias used unique

Keywords: kbmm KB140108