Draws the portion of the scroller’s track, possibly including the line increment and decrement arrow buttons, that falls in the given rectangle.
- macOS 10.5+
The rectangle in which to draw the knob slot.
YES, any scroll arrow button that falls within
slotis drawn highlighted; otherwise it's drawn normally.
Only one arrow button will be shown highlighted at a time, so you can expect this method to sometimes be invoked with a
slot that encompasses only one arrow.