From an email sent to Pavel and Artem on approximately November 24th titled "Hover bug in Popups":

This bug is similar to the last one I emailed about, where things in Popup are a little odd. This time, it is the hover property. Again, I've attached a modified HelloPopup sample application to demonstrate the problem. Essentially, hover is remaining true when it shouldn't be.

Here's how to recreate it the attached HelloPopup application:
1) Move the mouse in to the application and click the Popup button.
2) Move your mouse in and out of the popped up window - note the textfield properly states whether the mouse is hovering in there.
3) With your mouse in the Popup area (so the textfield says hover is true), press the Escape button. The popup should disappear.
4) Move back to the original window, and click the Popup button again.
5) Note that the text in the popup window still says the hover is true, even though the mouse isn't in there.

I would expect that hover is false in this situation. The reason this is a bug to me is shown in RT-18075. In short, a ComboBox list popup shows the hover highlight even when the mouse is no longer in the window. This leads to two items looking selected at a time.