NaroCAD uses the setting setup similar with Mac OS X/GNOME applications, meaning that the settings apply automatically. To make this happen, we use a mechanism that options are written in a NaroCAD document, and when a setup option will change, a notification is sent and all listeners.
This design is fairly inefficient as if for example you change a setting that will adjust the solver sensibility, as side effects, the all options reapply, like but not limited to: update tree view, resetup the color of background shapes, and so on.
Right now to be sure that the old code is not changed, the global notification still exist, but I've made that at least for solver, tree view and OpenCascade parts, they will not listen to global notification, but to the "solver section" ones which corresponds specifically when you change punctually the corresponding pages.
The main benefit will be that options in general will be far more responsive and you will see the applying of options regardless of the size of the future options dialog that they will not get slower and slower.
A small change is that right now there is an Zoom speed option to adjust nicely to your flows. More advanced options may follow later, but if you wanted to do precise drawing, you were out of luck in your previous work.