Yes you do get used to it, but since I move often from Inkscape / gimp and other visual creation tool (freecad and qgis to name a couple) it does create a 'strange' effect on the tracking
of the document.
I think what could work is a setting that specify where you want your zero mark for the ruler. So if your zero mark is always center, then you expect that behavior, or you can specify that the zero mark be on the left, as it is now, so that user could decide on the behaviour of the interface, which I think could help on modeling the tool for everyone's usage.
But that's just an idea, I am far from being able to put that into code
Thanks again for the excellent tool!