Yes to do what you need you simply need to change the xdg configuration for each existing user like so:
~/.config/user-dirs.dirs
XDG_DESKTOP_DIR="$HOME/Desktop"
...
XDG_MUSIC_DIR="/home/common/Music"
XDG_VIDEOS_DIR="$HOME/Movies"
And to make this something available to all users created simply edit this:
/etc/xdg/user-dirs.defaults
DESKTOP=Desktop
...
MUSIC=../common/Music
VIDEOS=Videos
To modify the permissions, this bit is tricky because you need to make sure that all files created in these directories remain editable by everyone. I found this interesting guide on the subject:
http://www.centos.org/docs/2/rhl-rg-en-7.2/s1-users-groups-private-groups.html
Which suggests doing the following to make the permissions sticky as well as adding the users all to a common group:
chown nobody:users /home/common
chmod 2775 /home/common
usermod -a -G users user1
You may want to change the umask setting to allow all files created to be modifiable by the anyone in the users group in that directory, edit /etc/profile and go to the bottom and change umask 022 to umask 002 This is considered secure since all users have their own primary user and really only effects shared directories like this one you want to make.
Let us know if it works well enough.
It's dependent on the icon theme. If the icon is not given by an absolute path, following rules are used to find the icon:
The lookup is done first in the current theme, and then recursively in each of the current theme's parents, and finally in the default theme called "hicolor" (implementations may add more default themes before "hicolor", but "hicolor" must be last). As soon as there is an icon of any size that matches in a theme, the search is stopped.
[...]
The lookup inside a theme is done in three phases. First all the directories are scanned for an exact match, e.g. one where the allowed size of the icon files match what was looked up. Then all the directories are scanned for any icon that matches the name. If that fails we finally fall back on unthemed icons. If we fail to find any icon at all it is up to the application to pick a good fallback, as the correct choice depends on the context.
See the Icon Theme Specification for details.
Best Answer
You cannot set the CWD inside a .desktop file. If you want an application to have a specific CWD, you will need to write a simple wrapper script for the application, that looks something like this:
You can replace
your_programthere with$@and run the script with your_program as an argument, likerun-in-dir.sh your_program. This way you can use the same script to wrap any program you want to start in that directory.