* issue 2890: Add an "ALT" sticker to the media preview container if there are descriptions
* issue 2890: Use end and start for positioning
* issue 2890: Adapt to new media view group
* issue 2890: Use an indicator overlay for every (single) preview image
* issue 2890: Reduce radius to match that of the preview layout
* issue 2890: Remove (again) unused code
* issue 2890: Set visibility in any case
* issue 2890: Use a translatable text for ALT
* issue 2890: Show ALT flag only when showing media
* issue 2890: Call doOnLayout on the layout wrapper
