xfwm4 - Introduction
The Xfce 4 Window Manager is part of the Xfce Desktop Environment. The command to run it in the foreground is xfwm4; to run it in the background use xfwm4 –daemon. The window manager is responsible for the placement of windows on the screen, provides the window decorations and allows them to be moved, resized or closed.
xfwm4 adheres strongly to the standards defined on freedesktop.org. Consequently, special features such as making windows borderless, or providing an icon for the application must now be implemented in the application; you can no longer use the window manager to force different behaviour. One of the great features of xfwm4 is its themeability; themes are available at Xfce-Look. The window decorations (borders, title bar and window buttons) can be configured by using window manager themes.
xfwm4 offers multi-head support, for both xinerama and real multi-screen modes, useful when you have more than one monitor connected to your computer.
xfwm4 can be run stand-alone, but if used this way, the Xfce Settings Manager will be required as a GUI to make configuration changes. Tasks other than managing windows, like setting a background image or launching programs, need to be performed by other modules.
xfwm4 includes its own compositing manager, which takes advantage of the new X.org's server extensions. The compositor is like a WM on its own; it manages a stack of all windows, monitors all kinds of X events and reacts to them accordingly. Having the compositing manager embedded in the window manager also helps keeping the various visual effects in sync with window events. If you want to use the compositor, you have to build xfwm4 using the –enable-compositor configure option. In any case, you can disable the compositor on xfwm4 startup using the '–compositor=off' argument.