What is a window manager?
Don't be angry, I know most know about this already but for all the beginners :)... a window manager is the application that literally "draws" all of those maximize/close/minimize buttons, title bars, panels... or all the graphical user interfaces of all programs (which are usually called "windows", these days).
So I think that anyone can see the importance of a Window manager by now. Although when it comes to GNU/Linux we have several window managers because unlike many other operating system, GNU/Linux is "scattered".
You know, the Kernel (the software of the OS that deal directly with your hardware) is developed separately and the desktops and lot other apps are developed somewhere else, unlike with MS Windows or Mac OSX where the entire OS is built by the same developers which has both good and bad aspects (story for another day eh ;-)).
For instance, the Qt/KDE desktop uses a window manager for creating its application GUI called Kwin. The Gnome desktop (2.x versions) uses one called Metacity. The X Windows system (which is the core and oldest of all "window drawing" apps for GNU/Linux) uses the Xfmw and the now famous (thanks mainly to Ubuntu actually) the "Compiz" (which is actually a dedicated 3D compositing manager) are just a few to mention.
The good old days ;-)...
The old days there weren't much 3D. In fact there wasn't any at all. So all these window managers, not that long ago were only capable of drawing 2D graphical user interfaces until recently the GPU devices became rather powerful and finally had the ability to draw 3D, complex GUIs.
So, most of those above mentioned WM were "patched" by the developers to enable the support for 3D rendering in GUIs which were only 2D in the recent past. With this trend, the WM received a lot of new features in general. One main one is called "compositing".
Although I won't be going into technical details... compositing in general is a must have (in both 2D and especially 3D) for enabling advanced features such as adding drop shadows, 3D effects, transparency, etc.
Some WM succeeded (such as the Kwin for instance) with this trend but some others like the Metacity wasn't that prominent.
Anyhow after sometime, the Gnome developers did some heavy coding into the Metacity concerning the upcoming Gnome 3 desktop (its already here, but you know in those days) for the future of 3D compositing and they called it Mutter.
So, even though Mutter is based on Metacity and Clutter... they're both separate projects. Thus the original Metacity WM that comes with the Ubuntu 11.04 (and below versions + with classic Gnome desktop) is still the old, 2d friendly WM that does not have the ability to create 3D GUIs. It's still a 2D window manager.
Anyhow, remember it may not be the most highly advanced WM when you make it the default compositing manager. And unlike with Compiz there aren't a lot of effects integrated into Metacity's compositing "engine" (no 3D effects to begin with) thus don't hope for a lot of effects.
But things like adding a drop shadow and adding transparency, etc are available and on the bright side, it won't take a lot of system resources when comparing with the other WM such as Compiz for instance.
Wait a second here Gayan!. If I cannot have any of those nerdy 3D effects then what do I get after enabling this "compositing" thing?
Well, um... okay, have a look at the below two screenshots.
The first one is a screenshot of Nautilus without any Metacity compositing but the second one was taken after the enabling it. Although there isn't much to talk about but you can see the second one has a nice drop shadow, faster minimizing effects (bit similar to the Compiz ones), etc ... for a start :).
|After enabling... well, better than nothing :/...|
And as mentioned, when the Metacity compositing is enabled, the application launcher of Unity 2D will have that transparency effect as well.
Anyhow, you can easily make Metacity the default compositing manger Ubuntu 11.04 Natty narwhal by following the below procedure. But remember, first you have to make sure that the desktop that you run is using the Metacity instead of any other WM that you have installed.
1. Open your GNU/Linux Terminal and enter the below command (yep, we're using the Gnome's setting manager).
gconf-editor2. Now this should open a Window similar to the below one. From the left side go to: "apps" - "Metacity" -> "General".
3. Now from the options that you'll get to your right scroll-down until you see a setting called "compositing_manager" which is disabled by default. All you gotta do to make Metacity the default Compositing Window manager is to click on the "check-box".
Then you should see a disappearance of the windows of your desktop (don't panic :D), wait for few seconds, if everything went well, then you should see all of your opened windows + this time they'll have some cool shadows, etc.
Now not just enabling compositing but as you can see, there are some other options that you can set such as...
*. Enable/Disable workarounds ("patches" for those "old" and troublesome apps to work with Metacity).
*. Audo raise delay.
*. Enable/disable titlebar display once maximized.
*. Reduce resources - A pretty helpful one from the bunch actually. It'll skip some of those heavy effects to save some of those CPU/GPU/RAM or system resources iof your poor PC/Laptop ;-) in general thus making the desktop much faster.
These are just a few to mention. But as you can see, in general, you can use this window to configure a lot of settings related to Metacity window manager.
That's it. Now we're done. Enjoy!.