Christof,
Cool! I didn't realize you could call the SetFocus() method of an object in the designer. I opened a form with a pageframe, selected the pageframe, then =aselobj(lax), then put the pageframe into edit mode and did lax[1].pages[3].setfocus() sure enough the page comes forward, but if I select any controls on the page the prop sheet is stuck in a Multiple Selection state.
The next time I tried this while writing this message it gets itself into another odd state where the pageframe goes out of edit mode with the correct page selected.
Did you ever see this kind of behavior in VFP5?