WPF Firing Validation Rules on Button Click

Question

I have created a Custom TextBox control which fires the ValidationRules on LostFocus event. But now I need to fire the same validation rules when the user clicks the button. I wrote an article about my custom TextBox control which you can read it using the link below:

http://highoncoding.com/Articles/578_Creating_WPF_TextBox_UserControl_to_Perform_Custom_Validation.aspx

Thanks,