In that case you should also somehow tell the user that there’s a problem with the field. For example, if the user presses Tab, clicks on another control, presses Enter to trigger the Accept button, or presses Esc to trigger the Cancel button.
For example, you could display an error message, change the field’s background color, or at least beep to let the user know that focus did not leave the field because something is wrong. The event triggers even if the user tries to close the form.
I have already posted a thread regarding this enquiry under the title of "Raising events manually" but I think i caused some confusion in the process so now I will attack it from another direction.
I need to determine what the Validating event of a control is pointing to and therefore be able to call it manually.
In my windows form projects , i have validated the fields using Boolean method.