Better support for displaying items & subcollections on mobiles

[tnajdek]

Currently we display "Items" node which then navigates to item-list.

A better solution would render items directly below subcollections (either a limited set with a button to show more or "infinite" loaded as needed). This solution however is not trivial, some concerns:

• Entire collection tree is currently rendered as a nested structure which would not work with "infnite-loaded" items. Adding fixed number of items into this structure might be possible but could have performance impact.
• There would be no table header (no ability to sort items, unless implemented elsewhere)