Combo box Selection

[TeeSee]

I have a small form with a comb box and a close button on it. If I
cause the combo to drop and type in the first letter "k" to take me to
the kays in the list then change my mind and click the CLOSE button
the combo afterupdate still fires and opens the next form to the
record that was hi-lited but not "actually selected" in the dropdown.
How can I get around this so that the combo will not execute unless
the actual record is CLICKED by a mouse?

Thank you