/datum/atom

The parent of all the objects that can appear in the game world - /area, /turf, /obj and /mob (atom!). All variables and procs shared by physical objects are defined here - it does not need to be created itself.

/proc

/Click(location, control, params)
/DblClick(location, control, params)
/MouseDown(location, control, params)
/MouseDrag(over_object, src_location, over_location, src_control, over_control, params)
/MouseDrop(over_object, src_location, over_location, src_control, over_control, params)
/MouseEntered(location, control, params)
/MouseExited(location, control, params)
/MouseMove(location, control, params)
/MouseUp(location, control, params)
/MouseWheel(delta_x, delta_y, location, control, params)