GNU Emacs 24.0.90.1 (x86_64-pc-linux-gnu, GTK+ Version 2.20.1) of 2011-11-03 on lychee, modified by Debian
Gtk theme is Murrine Brave Dark.
I modified these lines in gtkrc
GtkRange ::slider-width = 10 # Scrollbar width.
GtkRange ::stepper-size = 0 # Stepper height.
This is what the scrollbars look like in most other apps:
http://jaderholm.com/tmp/2011-11-04-scroll1.png(though Gedit and Gvim both display them wrong)
This is what they look like in Emacs by default:
http://jaderholm.com/tmp/2011-11-04-scroll2.pngNote that the slider is the right width, it's just the trough that is wrong.
If I use (add-to-list 'default-frame-alist '(scroll-bar-width . 10)) then they look correct:
http://jaderholm.com/tmp/2011-11-04-scroll3.png
I've seen this in other themes that I haven't modified myself.