Microsoft KB Archive/95500

= FIX: GPF When Close Form That Contains a Single MCI Control =

Article ID: 95500

Article Last Modified on 12/12/2003

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APPLIES TO


 * Microsoft Visual Basic 2.0 Standard Edition
 * Microsoft Visual Basic 3.0 Professional Edition
 * Microsoft Visual Basic 2.0 Professional Edition
 * Microsoft Visual Basic 3.0 Professional Edition
 * Microsoft Visual Basic 1.0 Standard Edition

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This article was previously published under Q95500



SYMPTOMS
When you have a single MCI control on a form and you set the hWndDisplay property to the form's hWnd, you will receive a general protection (GP) fault upon closing Form1 through the System Control of Form1. This problem does not occur when you have a second control on Form1 in which you set the HwndDisplay property to the hWnd of the other control.



WORKAROUND
Here's an example that shows how to work around the problem. The code listed below places a picture box on Form1, changes the BoarderStyle to '0' (None), and then places an MCI control on Form1: Sub Form_Load MMControl1.FileName = &quot;c:\vb\samples\mci\mcitest.mmm&quot; '** file in the ..\samples\mci directory of VB 2.0 MMControl1.hWndDisplay = Picture1.hWnd '** note the picture's hWnd is used in place of the form's.     MMControl1.Command = &quot;Open&quot; End Sub

Sub Form_Unload MMControl1.Command = &quot;Close&quot; End Sub



STATUS
Microsoft has confirmed this to be a bug in the Microsoft products listed at the beginning of this article. This problem has been corrected in Visual Basic version 4.0.



Steps to Reproduce Problem
 Start VB.EXE. Choose Add File... from the File menu and add the MCI.VBX file. Place an MCI control on Form1.  Place the following code in the Form_Load event procedure of Form1: Sub Form_Load MMControl1.FileName = &quot;c:\vb\samples\mci\mcitest.mmm&quot; '** file in the ..\samples\mci directory of VB 2.0 MMControl1.hWndDisplay = Form1.hWnd '** docerr DisplayHwnd on page 248 of Professional Features MMControl1.Command = &quot;Open&quot; End Sub   Place the following code in Form_Unload event of Form1: Sub Form_Unload MMControl1.Command = &quot;Close&quot; End Sub  Press the F5 key to run the example, which may result in a GP fault when you try to close Form1's System Control box. The GP fault address is 0001:2817.</li></ol>

NOTE: This example and any example of using the MCI control can be run only in Windows version 3.1 or in Windows version 3.0 with Multimedia Extensions. You need add the following line to the Multimedia Extensions section ([mci extensions]) of your WIN.INI file: MMM=MMMovie

Additional query words: buglist1.00 buglist2.00 buglist3.00 fixlist4.00 2.00 3.00

Keywords: kbbug kbfix KB95500

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