Description of the need The ability for a site builder to check a box and make a block into an accordion to save space on the page.

This came up with the new welcome block being proposed for the dashboard #3994. I think it would be great if the welcome block could be closed and why not provide this option for other blocks. I think it would be especially useful on the dashboard.

Alternatives that have been considered Is there a contributed module that accomplishes this?

I don't remember if I've used it. But there is at least one Drupal 7 contrib module that does this: https://www.drupal.org/project/accordion_blocks

...if not, then create a request for it to be ported: https://github.com/backdrop-ops/contrib/issues/349

GitHub Link: 
https://github.com/backdrop/backdrop-issues/issues/3995
GitHub Issue #: 
3995