Focus handling fixes
Summary:
- Fix keyboard nav on the desktop again.
BUG:399566
- Fix initial focus properly.
- Make sure when using arrows after starting Plasma or after clicking into empty space, the first selected item is always 0, not 1 or some random item based on previous activity.
- Make sure the view is always scrolled up when (re)opening the popup.
Reviewers: broulik
Subscribers: plasma-devel
Tags: Plasma
Differential Revision: https://phabricator.kde.org/D16106