Highlights or unhighlights the scroll button the user clicked.
- macOS 10.0–10.14Deprecated
The receiver invokes this method while tracking the mouse; you should not invoke it directly. If
YES, the appropriate part is drawn highlighted; otherwise it’s drawn normally.
This method has no effect in macOS 10.7 and later.
Drawing Scroller Parts
Draws the scroll button indicated by
arrow, which is either
NSScrollerIncrementArrow (the down or right scroll button) or
NSScrollerDecrementArrow (up or left).
Draws the portion of the scroller’s track, possibly including the line increment and decrement arrow buttons, that falls in the given rectangle.
Caches images for the scroll buttons and knob.