Plus one for this feature. Good and simple suggestion to make reusable blocks appear different from regular blocks to avoid accidentally editing them (unless you want to).
We use reusable blocks in a couple different ways, and maybe there’s a better way to do this.
The first way is for blocks that never change — say an editorial disclaimer added to an opinion article. This is a straightforward use and doesn’t give us any issues.
The other way is we use reusable blocks is as templates, for example when we insert affiliate links at the end of an article. Since the links are different for every article (but the formatting is not), we end up converting the reusable block to a regular block before modifying the links… that is, if we remember to do so. If we don’t remember, we have to undo the changes, save the block, remove it (since the ‘convert to regular block’ option disappears after editing), then re-add it, convert to a regular block, and then make the modifications again. It’s seriously a minutes-long process.
My idea is to add some kind of warning when you click to edit a reusable block. “Do you want to modify this reusable block, or convert to a regular block?” That would make things super clear and prevent accidental modifications.
Or maybe we should be using the template system somehow, rather than reusable blocks, for this type of situation?