Knowledge Base

PRB: ISMOUSE Function Always Returns .T. in Windows 95 & 98

Article ID: 190262

Article Last Modified on 5/12/2003

APPLIES TO

This article was previously published under Q190262

SYMPTOMS

When running Visual FoxPro versions 3.x and 5.x in Windows 95 or Windows 98, the ISMOUSE() function always returns .T. regardless of the presence of the mouse. However, the ISMOUSE() function works as expected in Windows NT.

CAUSE

Visual FoxPro is using the GetSystemMetrics API function to check SM_MOUSEPRESENT to determine if a mouse is present or not. If GetSystemMetrics returns zero (false), you would expect ISMOUSE() to return .F.. However, in Windows 95 or Windows 98, the GetSystemMetrics API always returns .T. regardless of the presence of the mouse.

STATUS

This behavior is by design.

MORE INFORMATION

Steps to Reproduce Behavior

  1. Make sure that a mouse is connected to the computer.
  2. In Visual FoxPro, create a .prg file and place the following code in the .prg file: 
          #DEFINE SM_MOUSEPRESENT  19
      DECLARE Integer GetSystemMetrics IN Win32api Integer
      ?GetSystemMetrics(SM_MOUSEPRESENT)
      ?ISMOUSE()
  3. Save and run the program.
NOTE: The GetSystemMetrics() and ISMOUSE() are returning .T.
  1. Shut down the computer and disconnect the mouse from the computer.
  2. Run the same .prg in Visual FoxPro again.
NOTE: The GetSystemMetrics() and ISMOUSE() still return .T. even if the mouse is disconnected from the computer.

If you repeat these steps in Windows NT, you receive a .T. for the first scenario and a .F. for the second scenario.

Additional query words: kbOOP kbvfp600

Keywords: kbprb KB190262


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