Since you are using a Window, why not move this from your Loaded event handler to a ContentRendered event handler.
Regards Peter From: [email protected] [mailto:[email protected]] On Behalf Of Greg Keogh Sent: Sunday, 24 July 2011 8:03 AM To: 'ozDotNet' Subject: FW: WPF Binding validation (2) It is a timing related quirk. In the Window Loaded event if I fire a timer after 0.5 seconds which runs this line: comboInstTitle.GetBindingExpression(ComboBox.TextProperty).UpdateSource(); Then the validation runs and the red box appears. However, using a timer is a stupid hack and was just an experiment. I now have to find a real fix. Greg
