关闭MDI表单和子级时如何正确提示用户？

Question

I'm writing an IRC client, where there is an MDI parent with Server and Channel windows. When you close a Server window, it prompts the user and if they want to close it, the connection to the server is closed etc.

I would like there to be only one prompt when the MDI parent is closed rather than a prompt for each server. The problem is when the user tries to close the parent, the child Forms' OnFormClosing is called before the parent's.

Answer 1

Another option is to catch the MDI "close" BEFORE the child windows using the MDI's DefWndProc and "kill" the child windows there.

''' <remarks>Intercept the user clicking on the CLOSE button (or ALT+F4'ing) before the closing starts.</remarks>
Protected Overrides Sub DefWndProc(ByRef m As System.Windows.Forms.Message)

    Try
        Const SC_CLOSE = &HF060 'http://msdn.microsoft.com/en-us/library/ms646360%28v=vs.85%29.aspx

        If (m.Msg = WndMsg.WM_SYSCOMMAND) _
        AndAlso (m.WParam.ToInt32 = SC_CLOSE) Then

            If (Not Me.ExitApplicationPrompt()) Then ' Do your "close child forms" here
                m.Msg = 0 'Cancel the CLOSE command
            End If

        End If

    Catch ex As Exception
        My.ExceptionHandler.HandleClientError(ex)
    End Try

    MyBase.DefWndProc(m)

End Sub

Answer 2

Modify the MDI child form's FormClosing event to the following:

private void MyChildForm_FormClosing(object sender, FormClosingEventArgs e)
{
    if (e.CloseReason == CloseReason.MdiFormClosing)
    {
        e.Cancel = true;
        return;
    }

    // Child window closing code goes here
}

And then put your global closing prompt/logic in the MDI parent form's FormClosing event. Hint: use this.MdiChildren in combination with window type tests, ie, childForm is IServerForm .