There's a slight problem with users-admin, the Users section of gnome-system-tools. It will be a problem for anyone with a screen less than 864 vertical pixels. I've tried this on OBubuntu, Bento2 and DebWeb. The users-admin window will open just fine, and all sections of the window are accessible. The problem occurs when you select a user and click the Advanced Settings button. Here's a screenshot from a 1024x768 screen.
As you can see, there are no Cancel or OK buttons.
The "Change Advanced User Settings" window can be resized horizontally, but not vertically. It's the vertical size that's the problem. In order to get to those buttons, I had to increase the screen size to 1152x864. I was then able to access them.
Those screenshots are from Bento2. So, I tried running the program as user root.
darrel@Bento:~$ sudo su
[sudo] password for darrel:
root@Bento:/home/darrel# users-admin &
[1] 3499
root@Bento:/home/darrel#
(users-admin:3499): Gtk-WARNING **: Theme parsing error: gtk-widgets-img.css:18:14: Theming engine 'unico' not found
(users-admin:3499): Gtk-WARNING **: Theme parsing error: gtk-widgets-img.css:23:14: Theming engine 'unico' not found
(users-admin:3499): Gtk-WARNING **: Theme parsing error: gtk-widgets.css:248:14: Theming engine 'unico' not found
(users-admin:3499): Gtk-WARNING **: Theme parsing error: gtk-widgets.css:366:14: Theming engine 'unico' not found
^C
root@Bento:/home/darrel# killall users-admin
[1]+ Terminated users-admin
root@Bento:/home/darrel#
The users-admin window comes up as ghosted and the program will not start. I had to issue a killall command to kill the process. The results are the same on OBubuntu. Both Bento2 and OBubuntu already have the gnome-system-tools package installed.
I installed gnome-system-tools with the --no-install-recommends switch on DebWeb. I then ran the users-admin program from the menu entry. Same deal. The "Change Advanced User Settings" window cannot be resized vertically. I tried running it from a terminal as root using gksu -u root users-admin. Again, the window came up ghosted and the program would not start. And, again, I had to issue a killall users-admin command to close the window.