xfwm4 is the default Xfce window manager which manages the placement of
application windows on the screen, provides beautiful window decorations,
manages workspaces or virtual desktops and natively supports multiscreen mode.
It provides its own compositing manager for true transparency and shadows. The
Xfce window manager also includes a keyboard shorcuts editor for user specific
commands and basic windows manipulations and provides a preferences dialog for
advanced tweaks.