Xop provides Tcl/Tk with access to various low-level X window system functions.
- in the GUTTER
- The ability to query arbitrary windows on Tk's display
- Access to and control of X cut buffers
- Bell frequency, volume, and duration control
- Access to X drawables, including dumping their contents to Tk images
- Querying and manipulation of the X event queue
- Reading of window-manager-related window properties
- Colormap control
These facilities are provided via xop. The intended purpose of the Xop package is to provide certain low-level X11 facilities required by window managers, but the package need not be used in that way.