KDE’s visual effects for windows and menus technically dates back to KDE 3. Experimental programs like kompmgr provided drop shadows and transparency for windows, and the KDE desktop itself had built-in support for basic menu transparency, shadows, and other effects.
With the coming of KDE 4, the number of effects has multiplied, and KWin (KDE’s window manager) is now on par with Compiz (a window manager with numerous desktop effects). Moreover, KWin’s primary advantage over Compiz is that it is part of KDE and integrates perfectly with the rest of the desktop. While support for Compiz has been added, there are still some outstanding glitches when run on top of KDE.
One misconception about desktop effects is that they are solely used to increase aesthetic appeal and add no practical functionality. The reality, however, is that many desktop effects provide accessibility features and productivity enhancements, but having an awesome-looking desktop certainly doesn’t hurt.
KDE will attempt to detect your graphics card and determine which effects will function. For most, this works just fine, but if not,you may need to install drivers for your graphics card that can support composite window managers.
To check the status of desktop effects, start System Settings and, in the “WorkSpace Appearance and Behavior” section, click “Desktop Effects“. Alternatively, you can press “Alt+F2″, type Desktop Effects, and press Enter.
“Enable desktop effects” should be checked, and the “Compositing State” should say “Desktop effects are active”. From this General tab, you can also select common settings, rather than configuring each effect individually.
If you ever need to stop desktop effects, click the “Suspend Desktop Effects” button or press “Shift+Alt+F12″ from anywhere in KDE. This is particularly useful if you are playing OpenGL or SDL games that behave erratically with effects enabled.
The second tab, called “All Effects” shows you every available desktop effect. The enabled effects will have a check in the left-hand box next to the name, and those that have available configuration settings will have wrench icons to the right.
The first section is Appearance, which, as the name indicates, contains effects that alter the appearance of the desktop and/or windows. Fade, for example, causes windows to fade in and out smoothly when they are opened or closed. A new feature, called Blur, will cause any translucent window components to blur the backgrounds behind them.
An example of an effect that has some practical value is “Taskbar Thumbnails”. With it, you can hover your mouse over a taskbar entry and see a small thumbnail image of the window. The thumbnail is updated in real time, so if a progress bar is moving, for example, the thumbnail will actually show you the progress as it increases. Shadows also provide depth to the windows, making it easier to distinguish one from another.
While only a few of the Appearance effects have true practical value, for the Accessibility effects, functionality is their primary purpose. For example, the Zoom function allows the user to mangify the entire desktop, zooming in or out with 3D smoothing, and Track Mouse helps a user locate the mouse on the screen.
Focus is another section of effects that offers some visually pleasing and practical benefits. Dialog Parent, for example, dims the parent window behind a dialog box, helping the user focus on the active box. Dim Inactive dims any window that is not the current one you are using, particularly useful for those who are easily distracted. With Slide Back, when you change the focus to a window other than the current one, it will pull the current window to the side and then slide it underneath, providing a more natural-looking change of focus.
The Window Management effects deal with the windows and desktop organization. Here, you can configure the windows switching, desktop switching, Desktop Grid, which allows you to zoom out and see all desktops, and Present Windows, which zooms out all windows so that you can select the one you want.
In the Tools section, you have useful tech/troubleshooting effects, one that shows the frames per second (FPS) for the current desktop, and one that shows “paint”, areas of the desktop that change or refresh.
Finally, in the Advanced tab of Desktop Effects, you can change the Compositing type. OpenGL provides the most effects but requires a 3D-capable graphics card and drivers. XRender works without 3D capability, but it also disables some effects. Most of the other settings in this section vary depending on the graphics card you are using. The best way to find the correct setting is to test them, but aware that some may not work at all.
KDE desktop effects add eye candy and functionality to your desktop experience. Furthermore, Plasma and some applications make use of the compisiting system to add further effects, providing the user with a visually striking desktop environment.