Almost all of the Flex components have mouseOver/mouseOut or rollOver/rollOut events. Requires that these events called not the mouse cursor, but on the other element, such as Image or Bitmap.
For example, there is a Colomn Chart and image animations above it and I need to get the data (colomn value or index) when the image is over the column. If it were a component, then I would use hitTest. But what to do if it is chart?