UV version: universalviewer@4.0.25

I'm submitting a: bug report => please fork one of these codesandbox examples with a repro of your issue and include a link to it below

Page area

thumbnails in gallery view

Issue description

The thumbnails in the gallery view cannot be accessed by keyboard, they are just skipped when tabbing.

Steps to reproduce

1. open this manifest
2. activate Icon gallery button in top right corner to trigger the gallery view
3. press tab key and observe focus moving into the gallery view: it goes to minus button, slider, plus button, and then moves outside the gallery view skipping all the thumbnails

Expected behaviour

keyboard users are able to tab to each item, including the thumbnails, so they are able to navigate and activate these thumbnails like users with a mouse

WCAG criterion

2.1.1 Keyboard (Level A)

Related code

<div class="wrap loaded" style="width: 120px; height: 150px;" data-link="class{merge:multiSelected toggle='multiSelected'}"><img class="thumbImage" src="http://images.eap.bl.uk/EAP500/EAP500_1_1/1.jp2/full/200,/0/default.jpg" style="">						<script type="jsv#1^"></script><script type="jsv/1^"></script>						</div>
</div>