PRB: GotFocus Event Fails If MsgBox Invoked in LostFocus Event

• Enterprise Edition of Microsoft Visual Basic, version 4.0a, for Windows
• Standard and Professional Editions of Microsoft Visual Basic for Windows, versions 2.0 and 3.0
• Microsoft Visual Basic programming system for Windows, version 1.0

SYMPTOMS

Invoking a message box from a control's LostFocus event will prevent the GotFocus event of the next selected control from executing.

CAUSE

This happens because the GotFocus event is not executed. Removing the message box from the control's LostFocus will allow the GotFocus event to execute as expected.

WORKAROUND

To work around the problem, set a flag in the control's LostFocus event procedure. Then call a generic test routine from the next control's GotFocus event, as demonstrated in the following example:

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

2. Create the following controls and properties for Form1:

      Control     Name     Property Setting
      ----------------------------------
      Text Box    Text1    TabIndex = 0
      Text Box    Text2    TabIndex = 1
      Text Box    Text3    TabIndex = 2
   
   

3. Add the following code to the general Declarations section of Form1:

   Dim LastControl As Control Dim CurrControl As Control

      Sub CheckLostFocus ()
   
        If (LastControl.Tag = "True") Then
           X%=MsgBox("Is the value OK ?", 36, LastControl + " has Lost Focus")
   
           If X% = 6 Then    'if YES
              LastControl.Tag = ""
              CurrControl.SetFocus
           Else
              LastControl.SetFocus
           End If
        End If
   
      End Sub
   
      Sub Form_Load ()
         Set LastControl = Text1     'set to the first editable control
      End Sub
   
   

1. Add the following code to the LostFocus event for EACH Text control:

      Sub Text1_LostFocus ()
         Set LastControl = Text1
      End Sub
   
      Sub Text2_LostFocus ()
         Set LastControl = Text2
      End Sub
   
      Sub Text3_LostFocus ()
         Set LastControl = Text3
      End Sub
   
   

2. Add the following code to the GotFocus event of EACH Text control:

      Sub Text1_GotFocus ()
         Set CurrControl = Text1
         CheckLostFocus
      End Sub
   
      Sub Text2_GotFocus ()
         Set CurrControl = Text2
         CheckLostFocus
      End Sub
   
      Sub Text3_GotFocus ()
         Set CurrControl = Text3
         CheckLostFocus
      End Sub
   
   

3. Add the following code to the Change event of EACH Text control:

      Sub Text1_Change ()
         Text1.Tag = "True"
      End Sub
   
      Sub Text2_Change ()
         Text2.Tag = "True"
      End Sub
   
      Sub Text3_Change ()
         Text3.Tag = "True"
      End Sub
   
   

4. Press F5 to run the program.

STATUS

This behavior is by design. It is a limitation of Visual Basic's MsgBox statement.

MORE INFORMATION

Steps to Reproduce Behavior

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

2. Create the following controls and properties for Form1:

      Control     Name     Property Setting
      ---------------------------------------
      Text Box    Text1    TabIndex = 0
      Text Box    Text2    TabIndex = 1
   
   

3. Add the following code to the Text1_LostFocus event procedure:

      Sub Text1_LostFocus ()
         MsgBox "Text1 has Lost the Focus"
      End Sub
   
   

4. Add the following code to the Text2_GotFocus event procedure:

      Sub Text2_GotFocus ()
         MsgBox "Text2 has Received the Focus"
      End Sub
   
   

5. Press F5 to run the program.