Comment 4 for bug 791509

Yes, I have followed the problem up to model.refilter() in TagsPageTreeView.set_tag_filter()
But I have observed that the tag tree shows the pages repeated several times. Let's suppose I have a notebook like this:
Page 1
         |
         |-Page 2
                   |
                   |- Page 21
         |-Page 3
then the pane shows:
>Page 1
    >Page 2
        Page 21
    Page 3
>Page 2
    Page 21
Page 3
Page 21

as you see, the number of lines in the tree is multiplied depending on the notebook's tree depth. So, a 300 page notebook can generate several thousand lines in the panel, making it not only slow but hard to use too.
A more efficient approach would be just to use the same tree the index tab uses and not show lower branches and leaves.
What piece of code populates the tag tree?