I would agree with FD, I had this a few years ago on a training trip into Doha with an A330. We were 15 nm 90 degree right base for 34 and ATC cleared us for the approach. Trainee reached up and hit the APP button just as i noticed the LOC index about 1/4 dot fly left. Aircraft immediately went LOC* and I took control pulling heading and resetting the right base trajectory we were on originally (poor trainee didn't know what had happened, bit of startle and surprise). I would suggest that to show the whole picture, you would need to have the ND up as well. The LOC index would be in the middle with (maybe, probably) a different heading to the LS course index. (unless it was paralleling as per FD above - see Resolute Bay as an slightly adjacent example).