Hi Billiam! Correct me if I'm wrong, but Deepdwn seemingly works as one big [knowledge] "base", like I think they say when it comes to note-taking software. All of the folders that have been added play a part, and if you want to temporarily take one out of the equation you have to remove it or ignore it. 

I would like to have more bases to keep things tidy, but I can imagine that if I asked to implement something like this, the UI would gain a new element with a slightly different or confusing design, people would definitely want or need to reorganize their folder structure, you would have to work more, etc. 

So I had this idea, which doesn't require any new interface changes: a folder focus. 

When you focus a folder, all of the other folders that aren't its subfolders are greyed out or removed from the view, and all the tags and categories not found in that folder go away too. (You could also choose in the settings if you want the function to focus on one folder only at a time, like a toggle, or the more you manually select). 

This means you could have a Worldbuilding folder for your fantasy stories and a Blog folder like in my mockup coexist better by not having their contrasting tags – like "Vacations" and "Side characters" – pile up on the side. 

I feel like this is better than an extra filter, like: Bases - Tags - Categories... and adding/removing folders. What do you think?