Q22374: How a DLL Can Display a Message Using MessageBox()

Article: Q22374
Product(s): Microsoft Windows Software Development Kit
Version(s): WINDOWS:3.0,3.1
Operating System(s): 
Keyword(s): kb16bitonly
Last Modified: 06-NOV-1999

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The information in this article applies to:

- Microsoft Windows Software Development Kit (SDK) versions 3.0, 3.1 
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SUMMARY
=======

In the Microsoft Windows graphical environment, it may be necessary for a
function in a dynamic-link library (DLL) to communicate some information to the
user. The MessageBox() API is available for this purpose.

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

If a function exported from a DLL displays a message box, one of the parameters
to the function should be the handle to a window in the application that acts as
the parent window for the message box. While the message box is displayed, if
Task Manager closes the parent application for the message box, the message box
is destroyed.

When a function in a DLL displays a message only in response to an error
condition, specify NULL as the value of the hWndParent parameter, as follows:

     MessageBox(NULL, "Hi there!", "DEMO", MB_OK);

After the user dismisses the dialog box, the focus returns to the window that
previously had the focus, as above. However, because the message box has no
parent window, closing one or more applications with the Task Manager does not
destroy the message box.

Note that the hWndParent parameter must not specify a child window, such as a
control in a dialog box. If an appropriate window handle is not readily
available, specify NULL for the value of hWndParent and specify the MB_TASKMODAL
flag in the wType (fourth) parameter. This prevents the user from interacting
with any windows of the current application without suspending other
applications.

Additional query words: 3.00 no32bit 3.10

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Keywords          : kb16bitonly 
Technology        : kbAudDeveloper kbWin3xSearch kbSDKSearch kbWinSDKSearch kbWinSDK300 kbWinSDK310
Version           : WINDOWS:3.0,3.1

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