Reference for unit 'gpm': Constants

`GPM_BOT`		Bottom of area.
`GPM_B_LEFT`		Left mouse button identifier.
`GPM_B_MIDDLE`		Middle mouse button identifier.
`GPM_B_RIGHT`		Right mouse button identifier.
`GPM_DOUBLE`		Mouse double click event.
`GPM_DOWN`		Mouse button down event.
`GPM_DRAG`		Mouse drag event.
`GPM_ENTER`		Enter area event.
`GPM_HARD`		?
`GPM_LEAVE`		Leave area event.
`GPM_LFT`		Left side of area.
`GPM_MAGIC`		Constant identifying GPM in gpm_Open.
`GPM_MFLAG`		Motion flag.
`GPM_MOVE`		Mouse move event.
`GPM_NODE_CTL`		Control socket
`GPM_NODE_DEV`		Device socket filename
`GPM_NODE_DIR`		Where to write socket.
`GPM_NODE_DIR_MODE`		Mode of socket.
`GPM_NODE_FIFO`		FIFO name
`GPM_NODE_PID`		Name of PID file.
`GPM_RGT`		Right side of area.
`GPM_SINGLE`		Mouse single click event.
`GPM_TOP`		Top of area.
`GPM_TRIPLE`		Mouse triple click event.
`GPM_UP`		Mouse button up event.
`_PATH_DEV`		Location of /dev directory.
`_PATH_VARRUN`		Location of run PID files directory.