FIX: Unloading a Form After Assigning Text Property Causes GPF

   #If Win32 Then

   Private Declare Function PostMessage Lib "user32" Alias _
   "PostMessageA"(ByVal hWnd As Long, ByVal wMsg As Long, _
   ByVal wParam As Long, ByVal lParam As Long) As Long

   #Else

   Private Declare Function PostMessage Lib "User" (ByVal hWnd As Integer,
   ByVal wMsg As Integer, ByVal wParam As Integer, lParam As Any) As
   Integer

   #End If
				

   Const NILL = 0&

   Const WM_SYSCOMMAND = &H112

   Const SC_CLOSE = &HF060
				

   PostMessage Form2.hWnd, WM_SYSCOMMAND, SC_CLOSE, NILL
				

MORE INFORMATION

Steps To Reproduce Problem

1. Start a new project in Visual Basic. Form1 is created by default. Add a Text box to Form1. In the Click event for Form1, place the following code:

      Private Sub Form_Click()
        Form2.Show 1
      End Sub
   
   					

2. From the Insert menu, select Form to add another form to the project. On Form2, place a Text box. Add the following code to Form2:

      Private Sub Text1_DblClick()
        Form1.Text1 = Text1
        Unload Me
      End Sub
   
   					

3. Run the project by pressing F5. Click on Form1 to show Form2 modally. Double-click on the text box in Form2, and a General Protection Fault occurs.

In one test on Windows NT 3.51, with the 32-Bit Edition of Visual Basic, the error message was:

In another test with, the 16-Bit Edition of Visual Basic, the error message was:

To work around the problem, place the declaration given in the Workaround Section above in the General Declarations section of Form2, and change the code in the DblClick event of the Text box on Form2 to:

   Private Sub Text1_DblClick()

   Const NILL = 0&

   Const WM_SYSCOMMAND = &H112

   Const SC_CLOSE = &HF060

   Form1.Text1.Text = Text1.Text

   PostMessage Form2.hWnd, WM_SYSCOMMAND, SC_CLOSE, NILL

   End Sub