How to Create a Modeless Dialog or Form in Visual Basic

MORE INFORMATION

The Windows API SetWindowWord() is used with the value GWW_HWNDPARENT to change the parent of the form that you want to be a modeless dialog. SetWindowWord returns the original parent's window handle that we need to restore when the form is unloaded to avoid a General Protection Fault.

Step-by-Step Example

1. Start a new project in Visual Basic. Form1 is created by default.
2. Add a second form (Form2) to the project.
3. Add a the following code to the Form_Load event for Form1:

      Sub Form_Load()
         Form2.Show      'display the child form
         Form1.Caption = "Parent"
         Form2.Caption = "Child"
      End Sub
   
   						

4. Add the following declarations to the general section of Form2:

      ' Enter the following Declare statement as one, single line:
      Declare Function SetWindowWord Lib "User" (ByVal hwnd As Integer,
         ByVal Index As Integer, ByVal wNewWord As Integer) As Integer
      Const GWW_HWNDPARENT = (-8)
      Dim OriginalParenthWnd As Integer
   
   						

5. Add the following code the Form_Load event of Form2:

      Sub Form_Load()
   
       ' Set parent for the toolbar to display on top of:
       OriginalParenthWnd = SetWindowWord(Me.hWnd, GWW_HWNDPARENT, Form1.hWnd)
   
       Me.Width = Form1.Width \ 3      ' Scale child form
       Me.Height = Form1.Height \ 3
   
      End Sub
   
   						

6. Add the following code the Form_Unload event of Form2:

      Sub Form_Unload()
   
        Dim ret As Integer
   
        ' Return the original parent handle to avoid a GP Fault
        ret = SetWindowWord(Me.hWnd, GWW_HWNDPARENT, OriginalParenthWnd)
   
      End Sub
   
   						

7. Press the F5 key to run the program. The child form is displayed as a modeless dialog of the parent form.