Initial goal:
Letting user select items one by one (with multiselect UDW) when placing galleries or content lists on a landing page, instead of selecting a container and retrieving all items within the container like Gallery and Contentlist blocks are doing. The value here is of course to increase a lot productivity of the editors building landing pages (preventing them from having to gather content items into browsers aside from editing the landing page).

Direction:
Adding manual selections of items in the existing Gallery and Contentlist blocks would generate a lot of complexity so that it can both work with containers and manually selected items. So our idea is to create a new block, a bit similar to the Embed block, but instead of selecting one single item, the block would allow multi-selection. We suggest to call it Collection.

One question remains: would this block be enough to deliver on the different use cases:

• gallery showing only images
• list of content of different types

We assume that this intelligence could be managed at the View level, one the user edit a Collection block and select a view, a view would also have a controller associated that would filter the items per content types as defined in the template (for instance to only display images if the view is a Gallery view). A controller might not be needed but feels like the correct way to do it.

user stories to create:

• as a user, when creating a Collection block on a landing page,
  I want to be able to select different content items with multi-selection UDW at and assign them to the block.
• as a user I want to be able to de-assign content items when editing the block