The actual capability is quite easy to install, however it is still very slow and very buggy. People use this capability when they want to make really good screen shots but be warned that it will get in the way of your normal productivity.
Firstly, you need Xorg 6.8.2 (or later if it exists yet).
Then edit your /etc/X11/xorg.conf file as root to include these lines (place them at the bottom, if you like)
Code:
Section "Extensions"
Option "Composite" "Enable"
EndSection
nVIDIA users have an advantage here: add Option “RenderAccel” “true” just underneath Option "Composite" "Enable" for speed
Next, you need
xcompmgr and
transset. Xcompmgr enables drop shadows, while transset enables window transparency. The method of installation will vary between the two, but you can just use
http://www.freedesktop.org/Software/xapps to find the two tarballs. Extract and install them as usual.
That's it. Restart X. You'll notice that the system will be a tad slower, this is normal due to the new extensions that you've made.
To enable drop shadows, simply type "xcompmgr -c". All your windows have drop shadows.
To make a window transparent, type "transset". Your cursor will change into a little crosshair; click on the window you want transparent, and it'll become transparent.
If you later decide that this isn't for you, just remove the Extensions section that you added in the /etc/X11/xorg.conf file. You don't need to uninstall the other two programs because they can't be used anyway without the extension.
Enjoy!
UPDATE: nVIDIA users, put RenderAccel in the setting under your display driver, not in the Extensions section.