when other treo application is active while an alert of calendar or task poped up, then the alert can be indicated by blinking asterisk icon on the left top corner of the screen.
for normal use of treo it is not needed of a stylus to touch the screen for activity.
first, i thought, i cannot displaying my alert window without touching the asterisk icon. somehow when i'm not in the mood to take off the stylus, i just using my finger to touch it.