xfwm4-dbgsym 4.12.4-0ubuntu1 (amd64 binary) in ubuntu zesty

 This package contains xfwm4 which is the window manager for Xfce4. It is
 designed to run with the rest of Xfce4 but makes a capable window manager
 for GNOME or KDE.
 .
 Install xfwm4 if you want a small, resource saving window manager which
 complies to the standards defined at http://www.freedesktop.org/. Without
 xfce4 installed this only gives you a window manager not the full
 environment.