Bug: Bookmarks popover closes when hovering over a bookmark

Clicking the bookmark door at the bottom of the column opens the bookmarks popover as expected, but moving the pointer onto the bookmarks inside it closes the popover. That makes it hard to reach any bookmark, or "Add This Page" / "Manage Bookmarks…" buttons at the bottom of the popover. Reproduction: 1. Click the bookmark icon next to the home button at the bottom of the tab column. 2. The bookmarks popover opens. 3. Move the pointer up over the list of bookmarks. 4. The popover closes before anything can be clicked.