PRB: Error Message "Invalid Procedure Call or Argument" While Modal Dialog or Form is Shown (242347)

The information in this article applies to:

Microsoft Visual Basic Learning Edition for Windows 5.0
Microsoft Visual Basic Learning Edition for Windows 6.0
Microsoft Visual Basic Professional Edition for Windows 5.0
Microsoft Visual Basic Professional Edition for Windows 6.0
Microsoft Visual Basic Enterprise Edition for Windows 5.0
Microsoft Visual Basic Enterprise Edition for Windows 6.0
Microsoft Visual Basic Standard Edition, 32-bit, for Windows 4.0
Microsoft Visual Basic Enterprise Edition, 32-bit, for Windows 4.0

This article was previously published under Q242347

SYMPTOMS

If a modal dialog or form is programmatically shown in code, other executing code in the same process that calls SetFocus on a control on a dialog or form other than the one currently modal raises the following:

Run-time Error '5'
Invalid Procedure Call or Argument

This only occurs when running the application as a compiled EXE. This does not occur in the Visual Basic IDE.

CAUSE

In the case of the SetFocus call, when a modal dialog, such as a messagebox or a modal Visual Basic form is shown, any other forms and their controls are disabled. Calling SetFocus on a disabled control always generates an error of this type.

RESOLUTION

There are several workarounds that can be used:

The most elegant workaround is to first check to see if the target of the SetFocus is Enabled.

The problem can be avoided by changing the repro sample code in the Timer event from this:

Private Sub Timer1_Timer()
        Command2.SetFocus
End Sub

to this:

Private Sub Timer1_Timer()
        If Command2.Enabled = True Then
             Command2.SetFocus
        Else
             Beep
        End If
End Sub

This works because whenever a modal dialog or form is shown, the controls on non-modal forms in that process become disabled.

Other ways that can work around this problem include:

Trapping the Error 5 within the procedure that actually calls the SetFocus.
Setting a global flag that becomes True when a call to MsgBox is made and check it before you make a call to SetFocus.

STATUS

This behavior is by design.

MORE INFORMATION

Steps to Reproduce Behavior

Start a new Standard EXE project in Visual Basic. Form1 is created by default.
Add two Command Buttons, Command1 and Command2, and a Timer control, Timer1, to Form1.

Add the following code to Form1:

Private Sub Command1_Click()
    MsgBox "Wait until the timer control fires"
End Sub

Private Sub Timer1_Timer()
        Command2.SetFocus
End Sub

Set the Timer1.Interval property to 3000 for a three-second delay.
Compile the project and run the newly-compiled EXE file.
Immediately after starting the application, click Command1 and wait for the Timer control to fire its Timer Event. When the event fires, you receive the error dialog described in the SYMPTOMS section above. After dismissing this dialog and the message box, your application terminates.

Modification Type:	Major	Last Reviewed:	6/24/2004
Keywords:	kbprb KB242347