Object Data Binding

Question

Hello all. I am having a problem. I am a student in college, working part time in the lab for a co-op. A student came in with a problem that I could not help her fix. The application has 2 textboxes for user input (width and height), and 2 read-only text boxes to display the area and perimeter of the shape. Also, there is a dropdownlist that has the items 'circle', 'square' and 'rectangle' in it. I need to use a databinding control to bind the text boxes so that when the focus leaves the 2 text boxes with user-defined values, the read only textboxes display the correct result for the shape that is selected in the dropdownlist control, without having to click any calculate button. Can anyone help me out with this? Thanks.