Dealing with Common Theme-related Problems

Since most programs are set up to use light-colored themes, you may encounter problems if you use a dark-colored or otherwise unusual theme. OpenOffice.org in particular has an annoying bug where the toolbar icons will switch to a rather awful-looking high-contrast icon pack without asking you when a dark theme is detected by the program. If the high-color icon pack is not installed, (as it seldom is out of the box) Openoffice.org will display text instead of icons, which looks even worse and is very space-inefficient. Fortunately, this problem can be easily dealt with.

The easiest way to rectify this problem is to change the icon pack in the OpenOffice.org configuration. (this is done through Tools → Options → View in OpenOffice.org) If the first method fails to work, there is a way to trick OpenOffice.org into using the icon set you want to use. OpenOffice.org stores its icon graphics in zip files, which makes them very easy to manage. These icon packs are buried rather deeply in the filesystem, so they can be difficult to find. Ubuntu stores them in /usr/lib/openoffice/share/config/, but the location varies from distro to distro. 

To fix the dark theme bug, all you must do is rename the icon pack of your choice (like images_human.zip) to “images_hicontrast.zip”. You should replace “images_hicontrast.zip” if it exists. After applying this fix and re-starting OpenOffice.org, OpenOffice.org will think it is using high-contrast icons, but it will actually be using the icon set you want to use and icons will look the way you want them to.

Sometimes, websites use stylesheets that conflict with your system colors, particularly if you use a dark theme with white text. Many stylesheets set a certain background color on form elements and neglect to set a particular text color. Quite often, this results in white or light-colored text on a light background, since system colors are used for any attributes not defined by stylesheets. Although you can configure Firefox to use system colors for web elements, this solution is often too imprecise and makes most websites look ugly. Fortunately, there is a better way.

One of Firefox's greatest strengths is its sheer hackability. Firefox has general settings in its about:config section that allow you to fine-tune the browser's performance and configuration, but Firefox can also be customized very precisely on a per-user basis. Each Firefox profile has its own userContent.css file. (not to be confused with userChrome.css, which is used to manipulate the Firefox GUI itself) userContent.css does not exist by default and must be created in ~/.mozilla/firefox/[your_profile_name]/chrome. Fortunately, Firefox provides a template to start with for both userContent.css and userChrome.css. userContent.css is used to declare rendering guidelines on either a global basis or for specific websites.

If you are using an unusual color scheme, you are able to use userContent.css to force Firefox to override a site's stylesheet in favor of your own preferences. As the extension suggests, userContent.css is just like any other cascading style sheet, but it does have a few Firefox-specific differences. If you have any CSS experience at all, you should not find it too difficult to configure userContent.css. (If you are new to CSS, it is easy to learn and rather straightforward) If you run into problems, there are many online guides that cover the differences between userContent.css and standard CSS in detail in addition to the many CSS tutorials out there.

Desktop Compositing

Many operating systems have shifted from using software rendering for desktop effects, instead opting for 3d-accelerated desktop effects. Linux has offered compositing features for years, starting with the original Compiz Quinn, followed by Beryl. Those two projects have culminated in Compiz Fusion, which is discussed in-depth in this section.

Compiz Fusion Overview

GNOME and KDE 3 have built-in interfaces to use Compiz Fusion, a desktop compositing tool and window manager that is a drop-in replacement for the Metacity Window manager in GNOME and the old Kwin window manager in KDE 3.5. KDE4 has its own compositing engine, but Compiz Fusion is able to override it. Compiz Fusion is a descendant of and replacement for Beryl, a compositing manager that was popular several years ago. Beryl was originally a fork of the original Compiz Quinn project; both projects are now obsolete.

Compiz Fusion uses your computer's 3d-acceleration capabilities to produce special visual effects that conventional software-driven graphics are not able to match. The extra burden of rendering these effects is shifted to the GPU on your graphics card or chipset (which would otherwise be idle) instead of the main CPU that is used for everything else. Because of this, you need to make sure your graphics card or chipset is supported in Linux and there is a driver for it if necessary if you want Compiz Fusion to work. (Nvidia support is very good from our experience) Compiz Fusion runs with very little overhead and does not slow down old or low-end machines.

Compiz Fusion can do much more than Windows Vista's “Aero” compositing engine. Although GNOME and KDE 3.5 include several presets on some distros, (notably Ubuntu) Compiz can be fine-tuned with the Compiz Config Settings Manager. (CCSM) CCSM can be invoked either through your favorite desktop environment/window manager's menu system or by typing “ccsm” into a terminal. (assuming that CCSM is installed)

Working with Compiz Fusion

CCSM gives you the full scope of effects that the Compiz Fusion engine is capable of. It can replicate all of the features that are in Vista's Aero, and Compiz still has plenty of unique features of its own that have been inherited from Beryl and the original Compiz. Many people have the misconception that Compiz Fusion is merely eye-candy that is meant to “wow” and impress new users. Although there is a grain of truth to that, it is not fair to over-generalize. While some of Compiz's functionality is purely decorative, (and can be way over the top if you use all of it at once) some of it is meant to compensate for certain disabilities or to help make using your computer easier.

For instance, the ADD helper tool can help those afflicted with the disorder by dimming all windows except the current active one to minimize distraction and to make the task at hand easier to focus on. Likewise, the magnifier tool makes text easier to read on programs that do not support dynamic text zooming and the negative tool can make some interfaces easier to read by inverting the colors. All of these effects could not be easily implemented through conventional software acceleration without slowing the computer down significantly.

On distros like Ubuntu, Compiz Fusion is installed by default but must be activated manually once the requisite video card drivers have been acquired. To enable Compiz Fusion in GNOME, go to System → Preferences → Appearance → Visual Effects and select the preset level you want or use CCSM to configure the desired effects. (CCSM is not required to use the presets in GNOME's Appearance module)