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[PRB] The focus doesn’t go to the parent window when closing a modal form

In some circumstances you might notice the following behavior in a migrated .NET program: a window opens a modal dialog form but when the user closes the modal form the parent window doesn’t receive the input focus and another window – possibly from a different application – becomes the foreground window.

This behavior is by no means caused by VB Migration Partner’s support library. In fact, you can see that many Windows user have observed the same behavior, as is apparent from many forum posts, such as:

http://www.vbforums.com/showthread.php?536413-VB-.NET-2008-Application-lose-focus-on-closing-a-modal-Form
http://stackoverflow.com/questions/10459791/showdialog-dispose-focus-to-another-open-application
http://go4answers.webhost4life.com/Example/mdi-app-loses-focus-different-45566.aspx

While the causes for this behavior remain unknown, we have added a couple properties to the VB6Form class that aim to reduce (and hopefully eliminate) this problem. These properties are OwnerWindowHandle (which permits to specify the parent window of a modal window) and ResetForegroundParentForm ( if true, the support library attempts to give the input focus back to the parent window when the modal window closes). The typical .NET code that uses these properties looks like this:

    ' VB.NET
    Dim frm As New Form1
    frm.ResetForegroundParentForm = True
    frm.OwnerWindowHandle = Me.Handle
    frm.Show(1)
 
    // C#
    Form1 frm = new Form1();
    frm.ResetForegroundParentForm = true;
    frm.OwnerWindowHandle = this.Handle;
    frm.Show(1);

In most cases the assignment to the OwnerWindowHandle property is optional, because the support library can deduce this value by itself. The assignment to the ResetForegroundParentForm property is also optional: if you want to apply it to all the modal window in your migrated project you can just assign True to the VB6Form.ResetForegroundParentForms static property (notice the plural):

    VB6Form.ResetForegroundParentForms = True
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