h-split/v-split jump around when used inside an element with position: relative

[p-himik]

h-split and v-split rely on offsetLeft and offsetTop, but these properties are calculated relative to the offsetParent, which is a closes positioned element. And the splits also use clientX and clientY, which are calculated within the viewport.
So, if the viewport does not coincide with the closest positioned element, a split's handler will jump on the first mouse move.

[Frozenlock]

Can confirm, bumped my head into the same issue.

[MawiraIke]

I have been able to reproduce this issue and fix it. I have changed the position calculation to be determined by using pageXOffset, pageYOffset and getBoundingClientRect which fix the issue. Thank you for spotting this.