DOCUMENT:Q170510
TITLE   :Double-Clicking the Mouse Button Acts as a Single Click
PRODUCT :Microsoft Windows NT
PROD/VER:4.00
OPER/SYS:WINDOWS
KEYWORDS:kb3rdparty kbbug4.00 kbfix4.00 nt32ap NTSrvWkst

--------------------------------------------------------------------------
The information in this article applies to:

 - Microsoft Windows NT Workstation version 4.0 Service Pack 3
 - Microsoft Windows NT Server version 4.0 Service Pack 3
--------------------------------------------------------------------------

SYMPTOMS
========

Double-clicking the mouse in your application behaves as if you clicked the
mouse button once. This behavior has been observed in the following
applications running in Windows NT 4.0 Service Pack 3:

 - Visio Professional 4.x

CAUSE
=====

Windows NT 4.0 Service Pack 3 adds a code path where mouse movement does
not update the timestamp for a WM_MOUSEMOVE event. This behavior can
potentially occur with any application that relies on WM_MOUSEMOVE
timestamps. For example, Visio uses a custom event handler to detect double-
clicks rather than checking for the WM_LBUTTONDBLCLK message.

RESOLUTION
==========

To resolve this problem, obtain the hotfix below, or wait for the next
service pack.

This hotfix has been posted to the following Internet location:

   ftp://ftp.microsoft.com/bussys/winnt/winnt-public/fixes/usa/nt40/
   hotfixes-postSP3/dblclick-fix

STATUS
======

Microsoft has confirmed this to be a problem in Windows NT version 4.0.
A supported fix is now available, but has not been fully regression-tested
and should be applied only to systems experiencing this specific problem.
Unless you are severely impacted by this specific problem, Microsoft
recommends that you wait for the next Service Pack that contains this fix.
Contact Microsoft Technical Support for more information.

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

Visio Professional is manufactured by Visio Incorporation, a vendor
independent of Microsoft; we make no warranty, implied or otherwise,
regarding this product's performance or reliability.

Additional query words: 4.00 prodnt single click

============================================================================

THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS
PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND.  MICROSOFT DISCLAIMS
ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES
OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.  IN NO
EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR
ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL,
CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF
MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE
POSSIBILITY OF SUCH DAMAGES.  SOME STATES DO NOT ALLOW THE EXCLUSION
OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES
SO THE FOREGOING LIMITATION MAY NOT APPLY.