- mouseout from a spinner button, but stay on border, don't mouseout of the outer element: the idle image displays correctly.
- Now mouseout slowly and all the way out of the element. Depending on how fast you move the mouse, you'll see the idle image flash before it disappears.
- You'll see the inverse on mouseover, idle flashing before the button's hover image displays.
I don't know if this is good or bad, it probably depends on who you ask. I wanted to note it as a known behavior.