Determines if a mouse event landed on a scrollbar rather than on element content. Scrollbar
interactions fire mouse events on the scrolling element itself (or on <html> for the page
scrollbar), so an outside-click check would otherwise treat dragging a scrollbar as a click away
from the pop-up and dismiss it mid-drag.
Determines if a mouse event landed on a scrollbar rather than on element content. Scrollbar interactions fire mouse events on the scrolling element itself (or on
<html>for the page scrollbar), so an outside-click check would otherwise treat dragging a scrollbar as a click away from the pop-up and dismiss it mid-drag.