Validating user interface in
This is a better way of displaying error messages than the old way of using message boxes because it eliminates at least two serious problems with message boxes: component shows the error icon and the error message in a nonintrusive way.
One of the useful techniques for restricting user input is selectively enabling and disabling controls.
When you want a control to respond, regardless of the validation status of other controls, you should set the component can set a small icon next to a field when it contains an error.
When the user moves the mouse pointer over the icon, an error message pops up as a Tool Tip.
This allows you to set up a two-tier validation on controls.