Mouse position is incorrectly detected on Safari

[computermacgyver]

I do not have access Safari to reproduce this, but Bernie was able to show me an error where the mouse was being detected over the wrong node (by a large range) resulting in strange hover/select issues.

Can any one with Safari reproduce this. This is a problem with the main branch of Sigma and not a regression.

[jthrilly]

I have observed this and discussed it with Bernie in the past. I believe there are issues related to XOffset and YOffset in general, which may also be affecting my attempts to introduce touch event support. As such I propose these issues be investigated together.