In mine, the file is located here.
/usr/doc/xfce-4.8/xfce-utils-4.8.3/html/C/index.html
It works for me because I have a bunch of links.
vector://usr/doc/xfce-4.8
mark:$ ls -l
total 72
lrwxrwxrwx 1 root root 12 Jan 15 05:32 Thunar -> Thunar-1.2.3/
drwxr-xr-x 3 root root 4096 Nov 3 2011 Thunar-1.2.3/
lrwxrwxrwx 1 root root 9 Jan 15 05:32 exo -> exo-0.6.2/
drwxr-xr-x 3 root root 4096 Nov 3 2011 exo-0.6.2/
lrwxrwxrwx 1 root root 12 Jan 15 05:32 garcon -> garcon-0.1.9/
drwxr-xr-x 2 root root 4096 Nov 3 2011 garcon-0.1.9/
lrwxrwxrwx 1 root root 21 Jan 15 05:32 gtk-xfce-engine -> gtk-xfce-engine-2.8.1/
drwxr-xr-x 2 root root 4096 Nov 3 2011 gtk-xfce-engine-2.8.1/
lrwxrwxrwx 1 root root 16 Jan 15 05:32 libxfce4ui -> libxfce4ui-4.8.0/
drwxr-xr-x 2 root root 4096 Nov 3 2011 libxfce4ui-4.8.0/
lrwxrwxrwx 1 root root 18 Jan 15 05:32 libxfce4util -> libxfce4util-4.8.2/
drwxr-xr-x 2 root root 4096 Nov 3 2011 libxfce4util-4.8.2/
lrwxrwxrwx 1 root root 17 Jan 15 05:32 libxfcegui4 -> libxfcegui4-4.8.1/
drwxr-xr-x 2 root root 4096 Nov 3 2011 libxfcegui4-4.8.1/
lrwxrwxrwx 1 root root 14 Jan 15 05:32 tumbler -> tumbler-0.1.22/
drwxr-xr-x 2 root root 4096 Nov 3 2011 tumbler-0.1.22/
lrwxrwxrwx 1 root root 16 Jan 15 05:32 xfce-utils -> xfce-utils-4.8.3/
drwxr-xr-x 3 root root 4096 Nov 3 2011 xfce-utils-4.8.3/
lrwxrwxrwx 1 root root 21 Jan 15 05:32 xfce4-appfinder -> xfce4-appfinder-4.8.0/
drwxr-xr-x 2 root root 4096 Nov 3 2011 xfce4-appfinder-4.8.0/
lrwxrwxrwx 1 root root 21 Jan 15 05:32 xfce4-dev-tools -> xfce4-dev-tools-4.8.0/
drwxr-xr-x 2 root root 4096 Nov 3 2011 xfce4-dev-tools-4.8.0/
lrwxrwxrwx 1 root root 17 Jan 15 05:32 xfce4-panel -> xfce4-panel-4.8.6/
drwxr-xr-x 3 root root 4096 Nov 3 2011 xfce4-panel-4.8.6/
lrwxrwxrwx 1 root root 19 Jan 15 05:32 xfce4-session -> xfce4-session-4.8.2/
drwxr-xr-x 3 root root 4096 Nov 3 2011 xfce4-session-4.8.2/
lrwxrwxrwx 1 root root 20 Jan 15 05:32 xfce4-settings -> xfce4-settings-4.8.3/
drwxr-xr-x 2 root root 4096 Nov 3 2011 xfce4-settings-4.8.3/
lrwxrwxrwx 1 root root 12 Jan 15 05:32 xfconf -> xfconf-4.8.0/
drwxr-xr-x 2 root root 4096 Nov 3 2011 xfconf-4.8.0/
lrwxrwxrwx 1 root root 15 Jan 15 05:32 xfdesktop -> xfdesktop-4.8.3/
drwxr-xr-x 3 root root 4096 Nov 3 2011 xfdesktop-4.8.3/
lrwxrwxrwx 1 root root 11 Jan 15 05:32 xfwm4 -> xfwm4-4.8.2/
drwxr-xr-x 3 root root 4096 Nov 3 2011 xfwm4-4.8.2/
lrwxrwxrwx 1 root root 18 Jan 15 05:32 xfwm4-themes -> xfwm4-themes-4.6.0/
drwxr-xr-x 2 root root 4096 Nov 3 2011 xfwm4-themes-4.6.0/
vector://usr/doc/xfce-4.8
mark:$
