>I see nobody answered this, did you ever solve the problem?
>
>What about an alternate interface that uses a combobox instead. In your case the user tabs or clicks to the textbox, then presses ctrl-n. With a combo then could just press "n". Saves a keystroke. Or you cold use radio buttons or in the valid of the text box replace "n" with "negative". Just some ideas.

This could'n work. Because texboxes has to be flexible with values. I mean not only "Negative " or "Positive"