I see that you use often add several categories when you upload screenshots. The categories are not really tags, but more or less "a couple of trees with some cobwebs". Usually it is sufficient to use one or maybe two categories as far out in the branches as possible.
To get an idea of the tree structure, click a category link at the bottom of a page and browse around the category pages (have you tested clicking the blue triangles in front of some subcategories?). Another tool I use a lot is the category tree browser.
Apart from that, please continue. :-)
I didn't even know it was the same category tree, thanks! I'm new to MediaWiki.