Q149487: BUG: Mouse Captured After Clicking DBGrid Column Header

Article: Q149487
Product(s): Microsoft Visual Basic for Windows
Version(s): 4.0
Operating System(s): 
Keyword(s): kbVBp400kbbuglist
Last Modified: 11-JAN-2001

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The information in this article applies to:

- Microsoft Visual Basic Standard Edition, 32-bit, for Windows, version 4.0 
- Microsoft Visual Basic Professional Edition, 16-bit, for Windows, version 4.0 
- Microsoft Visual Basic Professional Edition, 32-bit, for Windows, version 4.0 
- Microsoft Visual Basic Enterprise Edition, 16-bit, for Windows, version 4.0 
- Microsoft Visual Basic Enterprise Edition, 32-bit, for Windows, version 4.0 
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SUMMARY
=======

Clicking a column header in a DBGrid control of a Visual Basic program causes
the mouse to remain inside the borders of the column headers. The program only
responds to keyboard commands when the mouse cursor is trapped in the column
header.

WORKAROUND
==========

In order to work around the problem it is possible to add the following code to
the project. Because this problem should not affect the compiled executable, it
is possible to remove the workaround before debugging.

1. Add the following code to the General Declaration section of the form:

        #If Win32 Then
        Private Declare Function GetWindowRect Lib "user32" _
        (ByVal hWnd As Long, lpRect As RECT) As Long
        Private Declare Function ClipCursor Lib "user32" (lpRect As Any) _
        As Long
        Private Declare Function GetDesktopWindow Lib "user32" () As Long
        
        Private Type RECT
            left As Long
            top As Long
            right As Long
            bottom As Long
        End Type
        
        #Else
        Private Declare Sub GetWindowRect Lib "user" _
        (ByVal hWnd As Integer,lpRect As RECT)
        Private Declare Sub ClipCursor Lib "user" (lpRect As Any)
        Private Declare Function GetDesktopHwnd Lib "user" () As Integer
        
        Private Type RECT
            left As Integer
            top As Integer
            right As Integer
            bottom As Integer
        End Type

2. Add the following code to the click event before the Stop:

        Dim winrect As RECT
        #If Win32 Then
            Dim dskhwnd As Long
            Dim suc As Long
            dskhwnd = GetDesktopWindow()
            suc = GetWindowRect(dskhwnd, winrect)
            suc = ClipCursor(winrect)
        #Else
            Dim dskhwnd As Integer
            Dim suc As Integer
            dskhwnd = GetDesktopHwnd()
            Call GetWindowRect(dskhwnd, winrect)
            Call ClipCursor(winrect)
        #End If
        'Stop and/or all other code goes here

NOTE: All code should follow this patch code in the subroutine.

STATUS
======

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

MORE INFORMATION
================

To reproduce this behavior, add a DBGrid control to a form. In the click event
of the DBGrid control, stop the program by adding the stop keyword. When you run
the program and click the column headers of the DBGrid control, the mouse
pointer cannot be moved outside the borders of the DBGrid column headers.

Steps to Reproduce Behavior
---------------------------

1. Start Visual Basic or if it is already running, click New Project on the File
  menu.

2. Add a DBGrid control to the Form1 form.

3. Copy the following code sample to the Form1 code window.

        Private Sub DBGrid1_Click()
           Stop
        End Sub

4. On the Run menu, click start, or press the F5 key to start the program.

5. Click the column head of the DBGrid control. The cursor remains within the
  boundaries of the column headers.

Additional query words:

======================================================================
Keywords          : kbVBp400 kbbuglist
Technology        : kbVBSearch kbAudDeveloper kbVB400Search kbVB400 kbVB16bitSearch
Version           : 4.0
Issue type        : kbbug

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