GeezerVison

Instead of saving an array of end ticks for each tick, what if we save the end tick to each tick? Then you could check for an end tick on each tick and use a different code path. You'd also be able to get rid of the new arg in positionPeriodTicks.

Let me know if I didn't implement it as you intended.

What should happen if there's a major tick that doesn't coincide with a minor tick? Should that also be included?

No, when ticklabelindex is used, only minor ticks should labeled. This step is just to handle the special case when a minor tick coincides with a major tick in which case the major tick should be labeled instead (because the minor could be removed later).

Even if the major ticks aren't displayed, they're still used when determining which tick to display. From the description for ticklabelindex:

draw the label for the minor tick that is n positions away from the major tick

Without that major tick, the count will be off.

Thanks, now all major ticks and all non-overlapping minor ticks are in allTicklabelVals.

Even if the major ticks aren't displayed, they're still used when determining which tick to display. From the description for ticklabelindex:

draw the label for the minor tick that is n positions away from the major tick

Without that major tick, the count will be off.