INFO: Killing the Parent of a Modal Dialog Box (74474)
The information in this article applies to:
- Microsoft Windows Software Development Kit (SDK) 3.1
This article was previously published under Q74474
3.00 3.10
WINDOWS
kbprg
SUMMARY
An application cannot destroy the parent of a modal dialog box. When
the modal dialog box ends, control is returned to its parent. If the
parent is destroyed, control is given to a nonexistent window and the
application crashes.
When a parent window receives the destroy message, it is too late to
destroy a child modal dialog box. The destroyed dialog box does not
return control until after all the existing messages are processed,
including the final destruction of the parent window.
Therefore, it is imperative that all generational parents of a modal
dialog box be disabled and have no way of receiving a WM_DESTROY
message while the modal dialog box is active.
MORE INFORMATION
This situation does not affect modeless dialog boxes. Therefore, if
the design of a system cannot rule out the preceding problem, use a
modeless dialog box instead of a modal dialog box.
Because the Task Manager can kill any program at any time, there is no
absolute protection from the parent being closed. The optimal solution
is to forgo modal dialog boxes in favor of modeless dialog boxes.
When a modeless dialog box is created, it may disable its parental
windows.
Modification Type: | Minor | Last Reviewed: | 2/11/2005 |
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Keywords: | kb16bitonly kbDlg kbinfo KB74474 |
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