C# design problem

Question

Im writing an application that edits a large amount of data structures. I have a problem with how to design the saving functionality.

Whenever the user changes a value, I want the program to recognize this, and ask the user if they want to save when they try to exit without saving.

The only way I can think to do it right now would be to have a boolean valueChanged which initializes to false, and is set to false whenever the user saves. Then have it set to true whenever an change has been made. Problem is, this would take quite a bit of work to integrate it with all the controls.

Is there a better way to do this?