Issues with Arrowheads in X5

It all started when I accidentally edited Arrowhead 3. It ended up resized and with a gap between the arrowhead and the line itself. I've tried various combinations of "editing" and "attributes" via the outline pen/arrowhead options. So far, it seems to me:

"size" is some factor in relation to the line width, it's definitely not in mm (units I use).

"offset" is incremental i.e. if you set an offset then it moves the arrowhead relative to the location in previous version. Once you have it where you need it, the offset has to be set to zero, otherwise you'll move it again if you edit the arrowhead

Using these, I can move the arrowhead around, but when I set it so the point of the arrow is exactly on the logical end of the line (i.e. the end of the line if an arrowhead is not selected), then the arrowhead overlays  the line (rather than replacing that part of the line) so you end up with an arrow with a squared-end (= width of the line)

If I create a custom arrowhead, I get the same effect.

Any suggestions?

anyone know where are arrowheads saved in the corel folders/files?

... I did find other stuff, e.g. where the outline width selections are defined for all the various measuring units