Spinner tooltips and mouse cursors do not work reliably

Desktop Spinner tooltips and custom mouse cursors do not work reliably across the control's bounds. An inactive Spinner does not show its tooltip or custom cursor. For an active Spinner, they only work over the coloured arc, not the centre, corners, or rotating gap. A tooltip can repeatedly appear and disappear while the pointer stays still as the gap rotates beneath it.

The tooltip and custom cursor should work throughout the Spinner's bounds, whether or not it is active. The spinner itself continues to rotate; complete disappearance has not been reproduced.