Control Center - MDI settings

[Alexander Kirillov <kirillov math sunysb edu>]

Hi guys:
I was updating gnomecc docs and found a problem:

I can not figure out what "User Interface|MDI" is doing. Yes, I read
whta Dave wrote in users guide. But I still can not figure out the
difference between Modal and Toplevel. Worse, when I tried to see for
myself what these settings do, they didn't do *anything* for me at all
- all the apps I tried (from Gnumeric to gcolorsel) looked the same no
mattre what settings I set in "User Interface|MDI". Yes, I
did press "OK"  button, restarted the app, and tried to open several
docs at once. Gnumeric always creates separate windows for them and
gcolorsel always shows them in "notebook" style, wtih tabs on top - no
matter what. 

Is something worng with my sytem? Can someone verify on his/her system
if this works, and if so *how* it works?

Sasha