Well, I can't seem to access the subobjects list in the Properties Sheet with the keyboard. But I use the keyboard a lot in Form Designer.

From VFP's Help File:
Properties Window
CTRL+PAGE DOWN Move to next object in drop-down Object list.
CTRL+PAGE UP Move to previous object in drop-down Object list.
CTRL+END Move to last object in drop-down Object list.
CTRL+HOME Move to first object in drop-down Object list.