If I am entering information in the cell (not using a row edit template), and I want to promt  the user that something is invalid (I want to do this before the leave the row), what is the best way of doing that?

I tried using BeforeRowUpdate, but when I cancel the update it clears the entire row and I do not not want to do that. I want to set the cursor in the cell that has issue.

So I am look to prompt them before leaving the row and not loose any of my data if I cancel the update.

Any thoughts?

Thanks