HelenOS sources

PTD_DCLICK        160 uspace/srv/hid/display/input.c 	event.type = PTD_DCLICK;
PTD_DCLICK        501 uspace/srv/hid/display/seat.c 	    event->type == PTD_DCLICK) {
PTD_DCLICK        510 uspace/srv/hid/display/seat.c 		case PTD_DCLICK:
HelenOS homepage, sources at GitHub