Yelläks /ˈyæl•eks/

One advantage of using gnome-screensaver is that it is nicely integrated into the Gnome environment. However in the configuration dialog of the screensaver, where the user can choose, which theme should be shown, one important option is missing: An option that let the user set specific settings for the theme. For instance, if you want to display something more interesting than “jitu Linux 2.6.28-7″ when GLText is selected, there is no way to do so. In previous versions of Gnome the button was there, but later it has been removed due to some reasons, I do not agree with.

However, fortunately gnome-screensaver is nothing else than Xscreensaver except the integration into the Gnome desktop environment. To change the text of GLText or, as described in this example, the settings and directory of the slideshow “Carousel”, the user has to pin point exactly the place where to do so manually. There is also a tool (xFX Screensaver Settings) which helps especially unexperienced users to make the changes. However I personally did not want to install the Mono environment just for this particular application which I may use once a month. But enough of talking….

How to change the settings?

You need to install Xscreensaver and the themes you want. For that you fire up the package manager such as aptitude on the console or Synaptic and select Xscreensaver to be installed. xscreensaver-gl contains themes which needs a 3D accelerating graphics adapter. After that open a terminal and type

xscreensaver-demo

The preferences dialog of Xscreensaver comes up and with it the first error message already:

Warning:
The GNOME screensaver daemon appears to be running.
It must be stopped for XScreenSaver to work properly.
Stop the GNOME screen saver daemon now?

Hit the cancel button and viola the next error message comes up:

Warning:
The XScreenSaver daemon doesn’t seem to be running on display “:0.0″. Launch it now?

Also here: click on the cancel button. I will explain the necessary steps with an example. I would like to configure a theme called “Carousel” which shows my favorite photos 3D animated in a carousel. First I have to give a directory that contains the photos. This setting can be found in the register tab “Advanced”. It should be self explanatory here.

Second step: I would like to configure the speed the carousel turns and the number of photos shown. For that I went back to the register tab “Display Modes” and clicked on “Settings” (below the preview window). Make the necessary changes, after that click on “Advanced>>” and all options are replaced by a “Command Line”: carousel -root -duration 19 -speed 0.6883 -delay 23404 -no-titles

Open another terminal and change the directory to:
cd /usr/share/applications/screensavers/

Locate the file carousel.desktop and open it in an editor with root permissions (e.g. sudo nano carousel.desktop or su). The file looks like this:

[Desktop Entry]
Encoding=UTF-8
Name=Carousel
Comment=Loads several random images[...]
TryExec=carousel
Exec=carousel -root
StartupNotify=false
Terminal=false
Type=Application
Categories=Screensaver

The red marked line is the important one. It tells the screensaver front-end, what it should start with what parameters. Replace everything after “Exec=” by the text given in the “Command Line:” of the still opened Xscreensaver preferences dialog. If you are unsure, what to do, you can make a copy of the line and comment it out with a # to keep an original (in blue in the example below). My changed file looks like this:

[Desktop Entry]
Encoding=UTF-8
Name=Carousel
Comment=Loads several random images[...]
TryExec=carousel
#Exec=carousel -root
Exec=carousel -root -duration 19 -speed 0.6883 -delay 23404 -no-titles
StartupNotify=false
Terminal=false
Type=Application
Categories=Screensaver

That’s it basically. A preview of Carousel in the gnome-screensaver-with-no-settings dialog should show the theme with your settings. If your theme just vanished from the list, then you made a mistake in the file. Check it again. Since the settings are overwritten when the screensaver package is updated, it might be a good idea to keep a copy of the file. Another idea is to create another theme with your settings and a different name in a new file, which is not modified by the update process.

A few interesting links:

• gnome-screensaver settings – Ubuntu Forums
• HOWTO: Replace gnome-screensaver with xscreensaver – Ubuntu Forums