Just merged a PR to improve the function of the grainlines.
The grainline arrow length will no longer be a fixed size. The user can set a size from 25px to 200px in the Preferences:
This will have the effect that the grainlines will now size to the zoom scale.
Also fixed is limiting the minimum length of the grainline to twice the size of an arrowhead. This means the grainlines can no longer flip the arrowheads.
If only one arrowhead is used, the leader line will always be visible with at least a length of an arrowhead.
