One small testing file is attached:
when you run this file, please use tab key to move the focus to the list.
you would see: the focus is not drawn at this time although list gets the focus.
try to use arrow keys to select the list item, it won't work.

Then please use mouse to click one item, that item is highlighted, but focus seems still not drawn, there is no " focus border" surround that item. Try to use arrow keys again, they are not working. But when you hit enter, you would notice action event is invoked( on solaris ), that item must got focus already.

Try to move mouse to click some other components, for example you can click textField, then click the list again, you would notice this time the focus border is drawn on one item and arrow key is working fine to pick up the items
now.

(I don't know this is a bug or Motif list limitation, it works fine on windows.)