Is there anyway from the TextBox's LostFocus function to cancel it so the user is stuck in focus.

The reason I ask is that I want to validate the string in the textbox is a certain length. Currently when a user puts in a string longer than the allowed length a Messagebox displays and then the textbox is filled with a default value.

I'd like the user to be returned to the editing mode in the textbox with their original entered string so they can delete/edit it straight away.

Thanks