How can I override a handler for a Form ControlBox

In Pocket PC applications, you either have an Minimize (X) or a Close (OK) button in the upper right corner. Minimize is the default, which keeps the application running in the background. You can change the X to OK by doing adding the following line to the Form's constructor or InitializeComponent() method:
' Change Minimize (x) to Close (ok)

Me.MinizeButton = False
To override the Closing event, add this method to your Form:
Private Sub Form1_Closing(sender As Object, e As System.ComponentModel.CancelEventArgs) _

Handles MyBase.Closing

MsgBox("Closing App")

' do stuff

End Sub
For more information about Pocket PC form factors using the .NET Compact Framework, see:
http://msdn2.microsoft.com/en-us/library/bxz0e21k(en-US,VS.80).aspx
Also, see the Pocket PC User Interface Guidelines:
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/guide_ppc/html/ppc_pcconapplicationhelpforpocketpcs.asp
Hope this helps,

- Bruce Hamilton

.NET Compact Framework User Education