Merge pull request #6360 from dotCooCoo/fix/touchpad-ctrl-zoom

Canvas: Cmd/Ctrl-wheel input finer than a whole notch zooms; only whole notches scroll sideways

docs/mcp.md

@@ -3995,9 +3995,11 @@ desktop app): in View › Pixel Preview, on softens placed and embedded bitmaps;
 `disableAutoAddDelete` (off by default): on, the Pen no longer adds or deletes an anchor when a click lands on a
 segment or an anchor of a selected path.
 
-`ctrlWheelScrollsSideways` (on by default): on, Cmd/Ctrl-wheel scrolls the canvas sideways instead of zooming while
-`zoomWithMouseWheel` is off; off, Cmd/Ctrl-wheel zooms about the pointer. Alt + Cmd/Ctrl-wheel and a pinch on a Mac
-trackpad, on a touch screen or in the web build still zoom about the pointer. With `zoomWithMouseWheel` off, once a
+`ctrlWheelScrollsSideways` (on by default): on, Cmd/Ctrl with a mouse wheel's whole notches scrolls the canvas sideways
+instead of zooming while `zoomWithMouseWheel` is off; off, Cmd/Ctrl-wheel zooms about the pointer. Alt + Cmd/Ctrl-wheel
+and a pinch on a Mac trackpad, on a touch screen or in the web build still zoom about the pointer. Under either
+wheel preference, Cmd/Ctrl zooms about the pointer for the rest of a wheel turn once the turn has a trackpad event,
+point deltas from an unnamed source in the desktop app, or line deltas that are not whole notches. With `zoomWithMouseWheel` off, once a
 trackpad gesture holds Alt, it zooms until it ends, also after Alt is let go. The control channel's
 `ui.wheel` with `cmd: true` turns the wheel with Cmd/Ctrl held.