KB171972 - FIX: Cannot Disable UserControl on Modal Form

RESOLUTION

In the General Declaration section of the module, place the following declaration: (This must be declared as Private if it is included in a form module.)

      Private Declare Function EnableWindow Lib "user32" Alias _
         "EnableWindow" (ByVal hwnd As Long, ByVal fEnable As Long) As Long

The hWnd property, like all UserControl properties, requires a public property method to expose the property as part of the object's interface. Since you will not be setting a value, the Property Get is all that is needed.

      Public Property Get hWnd() as Long
         hWnd=UserControl.hWnd
      End Property

Next, you need to associate this method with the hWnd property of the control:

From the Tools menu, select Procedure Attributes.
Select "hWnd" from the Name drop-down list.
Click the Advanced button.
From the Procedure ID drop-down list, choose "hWnd." Click OK.

The EnableWindow function can now be called to enable or disable the UserControl. To disable the UserControl:

      Dim result as Long
      result = EnableWindow(Me.UserControl1.hWnd, 0)

To enable the UserControl:

      Dim result as Long
      result = EnableWindow(Me.UserControl1.hWnd, 1)

MORE INFORMATION

Steps to Reproduce Behavior

Create a new "ActiveX Control" project.

Add the following code to the UserControl:

      Public Property Get enabled() As Boolean
           enabled = UserControl.enabled
      End Property

      Public Property Let enabled(vNewValue As Boolean)
           UserControl.enabled = vNewValue
      End Property

      Private Sub UserControl_Click()
          MsgBox "Control is not Disabled."
      End Sub

From the Tools menu, select Procedure Attributes.
Click the Advanced button.
From the Procedure ID drop-down, chose "Enabled." Click OK.
Add a "Standard EXE" project.
Close the UserControl window, and add the UserControl to Form1.

Add two CommandButtons to Form1. Set the following properties.

      Name: Command1    Caption: "Enable Control"
      Name: Command2    Caption: "Disable Control"

Add the following code to Form1.

      Private Sub Command1_Click()
         Me.UserControl11.Enabled = True
      End Sub

      Private Sub Command2_Click()
         Me.UserControl11.Enabled = False
      End Sub

Add a standard module to the project.

Add the following code to Module1:

      Public Sub Main()
             Form1.Show vbModal
           End Sub

Run the project.
Note that clicking on the button labeled "Disable Control" does not prevent the message box from appearing when the UserControl is clicked.
Stop the project and open Module1.

In Sub Main(), change:

       Form1.Show vbModal

to:

       Form1.Show

Run the project again, and note that the "Disable Control" button now functions as expected and the message box does not appear.

FIX: Cannot Disable UserControl on Modal Form

SYMPTOMS

RESOLUTION

STATUS

MORE INFORMATION

Steps to Reproduce Behavior