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



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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

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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.



Dblclick-fix has been superseded by Getadmin-fix. You can find the latest

hotfix at the following Microsoft ftp site:



   ftp://ftp.microsoft.com/bussys/winnt/winnt-public/fixes/usa/NT40/

   hotfixes-postSP3/getadmin-fix



You can find the original hotfix at the following Microsoft ftp site:



   ftp://ftp.microsoft.com/bussys/winnt/winnt-public/fixes/usa/NT40/

   hotfixes-postSP3/archive/dblclick-fix



WARNING: If you install the original (archived) version of this hotfix

AFTER you apply the later version, your system may become unusable.

Microsoft does not recommend you install the original hotfix after applying

the later version.



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



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