FIX: CheckAutoCenter May Return TRUE with DS_ABSALIGN (132116)
The information in this article applies to:
- The Microsoft Foundation Classes (MFC), when used with:
- Microsoft Visual C++, 32-bit Professional Edition 2.0
- Microsoft Visual C++, 32-bit Professional Edition 2.1
This article was previously published under Q132116 SYMPTOMS
Positioning a dialog box, using DS_ABSALIGN and the Y axis screen
coordinate of zero causes the dialog box to be centered within the
application's main window.
CAUSE
The function Dialog::CheckAutoCenter() is called to determine whether the
dialog should be centered. In the case of y == 0, CheckAutoCenter() will
always return TRUE. This happens because of the following code from
CheckAutoCenter() in WINCORE.CPP:
BOOL bResult = !(lpTemplate->style & DS_ABSALIGN) &&
lpTemplate->x == 0 || lpTemplate->y == 0;
Note that because of the way C/C++ handles logical expressions, if
lpTemplate->style == DS_ABSALIGN, then lpTemplate->x == 0 will not be
evaluated. However, lpTemplate->y == 0 is evaluated and therefore is
capable of returning TRUE to CheckAutoCenter().
RESOLUTION
Do not use a Y coordinate of zero with DS_ABSALIGN.
STATUS
Microsoft has confirmed this to be a bug in the Microsoft products listed
at the beginning of this article. This problem has been fixed in Visual C++
5.0 for Windows.
MORE INFORMATION
To reproduce this problem set the DS_ABSALIGN style and a y position of
zero for the about box of a standard Appwizard-generated application.
| Modification Type: | Major | Last Reviewed: | 10/17/2003 |
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| Keywords: | kbBug kbfix kbNoUpdate KbUIDesign kbVC500fix KB132116 |
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