I also really want a feature like this.
Motiviation: in Roam, I can open like ~10 documents in the sidebar and I can ‘collapse’ each one, so that with one click I can expand any of the 10 documents and start editing, but since they’re collapsed they don’t take up much space.
In Obsidian if I want 10 documents open, they each need to either take up a lot of space, or if I resize them manually I need to resize them manually each time I want to edit them – a huge hassle.
Here’s an implementation that solves this problem: if you click on the title bar of a document, then if there are any other documents open in the same vertical column as the document, it collapses to only the title bar. Clicking on the title bar again expands it to its previous size. This would allow you to have a ‘stack’ of collapsed documents in a column on the right of the UI, and open/edit any of them with a click.