Pure step-size + next-position math for nD navigation. Computes how
far to move per [/] key press or slider wheel notch — the modifier
tiers (Shift fine ÷10, Ctrl coarse ×10, Ctrl+Shift extra-fine ÷100)
only reach here from the slider wheel: the [/] key bindings match the
unmodified key, so Shift+[ arrives as '{' and never fires — and where
the next position lands, including discrete rounding and wrap-around
or clamping at the dimension's bounds.
Pure step-size + next-position math for nD navigation. Computes how far to move per [/] key press or slider wheel notch — the modifier tiers (Shift fine ÷10, Ctrl coarse ×10, Ctrl+Shift extra-fine ÷100) only reach here from the slider wheel: the [/] key bindings match the unmodified key, so Shift+[ arrives as '{' and never fires — and where the next position lands, including discrete rounding and wrap-around or clamping at the dimension's bounds.