X window manager: Encyclopedia II - X window manager - How window managers work

X window manager - How window managers work

When a window manager is running, some kind of interaction between the X server and its clients is redirected through the window manager. In particular, whenever an attempt to show a new window is made, this request is redirected to the window manager, which decides the initial position of the window. Additionally, most modern window manager are reparenting, which usually lead to a banner being placed at the top of the window and a decorative frame being drawn around the window. These two elements are controlled by the window manager rather than the program. Therefore, when the user clicks or drags these elements, it is the window manager that takes the appropriate actions (such as moving or resizing the window).

Window managers are also responsible of icons. Indeed, icons do not exist at the X Window core protocol level. When the user requests a window to be iconified, the window manager unmaps it (makes it non-visible) and take the appropriate actions to show an icon in its place. Some window managers do not support icons.

While the main aim of window manager is, as suggested by its name, to manage the windows, many window managers have additional features such as handling mouse clicks in the root window, present panes and other visual elements, handling some keystrokes (e.g., Alt-F4 may iconify a window), deciding which application to run at start-up, etc.

Adapted from the Wikipedia article "How window managers work", under the G.N U Free Docmentation License. Please also see http://en.wikipedia.org/wiki