KWin

KWin is a window manager for the X Window System and a Wayland compositor. It is released as a part of KDE Plasma, for which it is the default window manager. KWin can also be used on its own or with other desktop environments.

KWin can be configured by scripting using QML or QtScript, both of which are based on ECMAScript.

Look and feel
There are many window decorations for KWin, including the current default Breeze (shown below), the previous default Oxygen, Microsoft Windows-like Redmond, and Keramik.

Compositing
Currently available compositing backends include OpenGL 1.2, OpenGL 2.0, OpenGL 3.1 and OpenGL ES 2.0.

Included effects
As of KDE 4.3 the following effects are built-in: