title: Dynamic updating of Activex Textbox entries
body: <p>I have 4 activex text boxes in which values (numbers) are entered.  The 5th text box is the sum of the first 4 text box entries. I want the 5th text box to update dynamically when the value in one or more of the first 4 text box values is changed by a user.  The first 4 boxes are named "TextBox1, TextBox2..., and the 5th is TextBox5. What would be the code to do this?</p>