Here is a sample of a confirm form. This form will only allow user to exit if the user click on undo or save. The usage of this form is for critical situation.
use this method with dialog mode and you have full control of user actions(except when computer crash).

Thinh

could add code to the form's Undo event, similar to the Undo-button's code, in case the user hits the escape key.

Cool, didn't thought off that. Your respond actually answer a different question that I so i appreciate the feedback.