Compositing window manager

A compositing window manager, or compositor, is a window manager that provides applications with an off-screen buffer for each window. The window manager composites the window buffers into an image representing the screen and writes the result into the display memory.

Compositing window managers may perform additional processing on buffered windows, applying 2D and 3D animated effects such as blending, fading, scaling, rotation, duplication, bending and contortion, shuffling, blurring, redirecting applications, and translating windows into one of a number of displays and virtual desktops. Computer graphics technology allows for visual effects to be rendered in real time such as drop shadows, live previews, and complex animation. Since the screen is double buffered, it does not flicker during updates.

The most commonly used compositing window managers include:

The window manager sends each window a message to repaint itself whenever appropriate (such as when it is resized, or when another window passes in front of it). With a stacking manager, the repainting process can become corrupted when a program that is slow, unresponsive or buggy does not respond to messages in a timely manner. A malicious program can cause the system to appear unstable by simply neglecting to repaint its window. Then, one or more of the following conditions may result:

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