28bb0c1fb2
Force an allocation at thumbnails creation so we can figure out whether we need to scroll when selecting. We also need to show() the whole AltTabPopup before calling _select() so that, when computing the scrolling offset, the widgets already have their styles loaded. Otherwise we will miss the switcher list item container's spacing. https://bugzilla.gnome.org/show_bug.cgi?id=655069