Our usage of pop-ups continues to be a problem. For other pop-ups like RecentProjects, or menus in the Editor and here we have to manually handle the close event when scrolling. In those cases, `Menus.closeAll()` works based on the CSS class used. `DropdownEventHandler` uses `PopUpManager.removePopUp()`. I don't think it's worth addressing here, but maybe we can file a code cleanup bug to consolidate the `scroll` event handling in these cases.