Updated: January 3, 2014
Here's a scenario. You have installed a Linux distribution like openSUSE or maybe Kubuntu, and you have enjoyed the desktop effects without fail for many weeks or months. Then, suddenly, one bright day, they stop working. You get all kinds of weird messages popping to your desktop, informing you how this and that effect cannot be enabled. What now?
This very short and simple tutorial will teach you how you can overcome this seemingly baffling problem, so you get your desktop effects back. As we know, they are a powerful weapon in one's arsenal, and when you need to impress people, this is the best way of doing that.
Problem + solution
So we're discussing KDE, right. Another important clarification is that the desktop effect used to work in the past, so you're not facing a more complex problem of not being able to enjoy them in the first place. Moreover, we will not be discussing the graphics card drivers, as they are often needed to make the desktop effects possible. Anyhow, you're seeing something like below:
The popup reads: The following desktop effects could not be activated, and then, there's a list of several desktop effects failing, like for example the desktop cube, snow, wobbly windows, and others. Not a good thing. You try fiddling with the menu, but it does not help at all.
To resolve the problem, we will simple move the kwinrc file from our home directory. This file contains various settings and configurations for your window manager, dictating the placement and feel of items on your desktop, as well as the behavior. It is quite possible that some of the directives may have gone corrupt, or they simply might be incompatible with whatever you're currently using, including a selected theme or window decoration.
The file is located under:
/home/<username>/.kde4/share/config/kwinrc
Just search for it, and then move it aside. Do not delete it, so you sort of have a backup. Once this is done, on next login to your system, the file will be automatically created, and you will have your desktop effects back.
Log out, log back in
And you should be fine. Test to verify it's all jolly good.
More reading
If you're interested, then you might want to check these:
openSUSE Nvidia graphics card installation
Kubuntu 13.04 Salamander review
Conclusion
Here we go. A seemingly destructive, irrecoverable problem, without any highly verbose or useful messages lying around the system, resolved. There's nothing to it really, just moving aside a possibly corrupt configuration file, which dictates how your KDE desktop behaves. Sometimes, in between updates and your attempts to make the desktop more presentable with new decorations and changes, the window manager settings might get borked. The solution is to move them aside and start from scratch.
Anyhow, this short article does not teach much, except to have hope in Linux problem solving not requiring a complete reinstall, as well as how to work with hidden configuration files that dictate the system look & feel. Knowing your way around KDE can help save you much frustration, as well as allow you easier migration and deployment of your favorite perks between distros or sessions. That would be all for this time. Party on.
Cheers.