GNOME - always on top

How to permanently set application window to be always on top in GNOME? Yes, you can right click on window header in GNOME, and check always on top. Unfortunately, after closing window, this setting will not remain. In three steps, I will show how to set calculator (gcalctool) to stay permanently above ...

1) Install Devil's Pie (a small window-matching utility)

yum install devilspie
# or
yum install gdevilspie

2) Create gcalctool.ds file in ~/.devilspie directory and put the following lines:

(if
    (is (application_name) "gcalctool")
    (begin
       (above)
    )
)

3) Set Devil's Pie to startup on user login in session manager

# open Sessions preferences and add startup program
System -> Preferences -> Personal -> Sessions [Add]

# fill the input fields:
Name    -> Devil's Pie
Command -> /usr/bin/devilspie
Comment -> gcalctool stays on top

The described procedure about making windows "always on top" is not crucial, but I hope it is helpful.