BUG: GP Fault When KEYSTAT.VBX Used in Two or More Apps

- Professional Edition of Microsoft Visual Basic for Windows,

  version 3.0

SYMPTOMS

When the KEYSTAT.VBX control is used in more than one application, and the parent window is minimized, the application causes a general protection (GP) fault.

STATUS

Microsoft has confirmed this to be a bug in the Microsoft product listed at the beginning of this article. We are researching this problem and will post new information here in the Microsoft Knowledge Base as it becomes available.

WORKAROUND

To work around this problem, use the Windows API GetKeyboardState function directly as in the following example:

1. Start a new project in Visual Basic. Form1 is created by default.

2. Add the following code to the (general) (declarations) section

      Declare Sub GetKeyboardState Lib "User" (ByVal lpKeyState As String)
      Const VK_SHIFT = &H10
      Const VK_CAPITAL = &H14
      Const VK_NUMLOCK = &H90
   
   

3. Place a command button (Command1) on Form1, and add the following code to the Command1 Click event:

      Sub Command1_Click ()
         Dim keys As String
         keys = Space$(256)
         GetKeyboardState keys
         If &H1 = (Asc(Mid(keys, VK_CAPITAL + 1, 1)) And &H1) Then
            Debug.Print "Caps lock"
         Else
            Debug.Print "non caps"
         End If
         If &H1 = (Asc(Mid(keys, VK_NUMLOCK + 1, 1)) And &H1) Then
            Debug.Print "Num lock"
         Else
            Debug.Print "non lock"
         End If
      End Sub
   
   

4. Run the application.