Hmm
Using my old Lazurus I see the AutoDropDown drops down when you select a different control.
Using the Trunk, it seems AutoDropDown does not work anymore, does nothing.
as for the older test, all I did was change the TAB order and that cause the combobox to drop down when I clicked on a different control.
But like i said, don't seem to work anymore in trunk, unless there is some secret code I 'am missing?
EDIT:
Apparently there is a bug in my older version of Lazurus.
I am not going to worry about it.
But in any case you can use the DroppedDown property at anytime to drop it, in the OnEnter, onClick etc.