Only show tag in the notebook we choose

When we choose one notebook, if it only shows the tags in this notebook, I think it will be more convenient. Because we can find which we want quicker. If we choose a tag, It only shows the tags with this tag, We can narrow the search range through this.

I consider about it for one day. I think that supporting multi-tag search may be implemented easilier!

Having sooo many tags I would also find this very useful. And not only tags per notebook but per note, as well. Going through the list of all tags in order to find tags active in a note takes a lot of time.

Would it be very difficult to implement?