Tie displayed incorrect if start and end notes have different clefs

Sometimes a picture is pretty explanatory:

This was broken in 3.0.5 because we always used the y position of the start note for both ends of the tie. Then it got fixed by my changes to support cross-staff ties, then broken again by my change to force ties to be horizontal otherwise. So, I guess I can't count this as a regression against 3.0.5 - just against the week or so it was working between those two changes :-)