When interacting with elements on the page, if any content appears on hover or focus and disappears when hover or focus leaves (like a dropdown or a tooltip).
First verify that the content disappears when hover or focus leaves. If the content is persistent on mouseout/focusout events, this criterion is inapplicable.
Ensure that the item can be dismissed without moving hover or focus. The most common way of making this happen is by making the ESC key get rid of the popup.
