Improving default ticks in Highstock Charts about highcharts

[TorsteinHonsi]

Thanks for writing!

1. The last label is cut off because there is no more space to the right in this chart. If we add a chart border, it's more clear: https://jsfiddle.net/highcharts/rb829ohz/ . You could disable the ellipsis, but I wouldn't recommend it because it causes the label to overflow both left and right: https://jsfiddle.net/highcharts/rb829ohz/1/ . A slightly better solution in this case would be to increase the right margin, though in other cases it may be wasted space: https://jsfiddle.net/highcharts/rb829ohz/2/
2. This is how tickPixelInterval works. There will be threshold values, so that when the length of the axis passes a certain threshold, the tick interval will be recomputed to fit a certain tickPixelInterval setting. You can think of this as responsive breakpoints, and in this case adding the y-axis title caused the axis to pass the breakpoint.
3. They will never be exactly the same because non-ordinal axis are linear. With ordinal axes we have a more complicated algorithm to lay out the ticks. It is a compromise between applying ticks to higher-order datetimes (midnights over regular hours, month starts over other dates etc), and a sensible spacing of the ticks.