Toolbar pallette items sometimes "hangs" as hovered

Toolbar pallette items in top tool bar or sidebar, is sometimes
left as if selected. Then You think “I didn’t use that command
just before”. Seems random to me which items are left selected.
Hovering the mouse over the item and then back to main viewport
"unselects" the item.

This is an OS X bug in the tool palette that has been there forever. It is Apple code that is tracking the cursor location then drawing and erasing the button outlines. The solution would be to not highlight the button at all, but I don’t think that is a very good solution.