Maybe I'm misunderstanding, but there is a Select on Floor Plan button just to the right of Header Options at the top of the ArchiCAD 10 schedule window. You must select an object in the schedule to make it active.
Regards,
Geoff Briggs
I & I Design, Seattle, USA
AC7-28, M1 Mac, OS 15.x
Graphisoft Insider's Panel, Beta Tester