quirky custom control

[steve]

i've built serveral controls designed for touch-screen use. i have a quirk
with one and am not sure how to solve the problem. it is a drop-down style
combo box that filters list items as the input text is changed. the list
inherits control and the editable portion inherits from textbox.

i've made it so that when an item in the list is selected, the next control
on the form gets focus...as if the user hit the tab key. when focus is lost
on this custom combo box, the drop-down list hides itself. this usually
works just fine, however the ui has some cpu consumptive validation that
occurs when it checks the data that was input...such that if the user hits
tab numerous times right after selecting an item from the list, focus ends
up god-knows-where. that's not the problem though. the problem is that some
of my custom combo's get and loose focus during this process and their lists
show but never hide when they loose focus in this manner.

any ideas on how i can insure that the drop-down portion of my combo will
hide itself *every* time it looses focus regardless of queued messages?

tia,

steve