Currently Treeviews does a great job at telling pageviews around a topic, when the main-space content is what needs to be measured. However, for projects like The Wikipedia Library, part of our impact is how many users use services like [[en:WP:Reference Desk]] or open projects like WP:TWL. It would be awesome to add to Treeviews (http://tools.wmflabs.org/glamtools/treeviews/) or similar the ability to select which namespace can be measured, and collected within a category. For example, we would like to be able measure pageviews for https://en.wikipedia.org/wiki/Category:The_Wikipedia_Library on both English, and across the other language communities. This might partially be dependent on https://phabricator.wikimedia.org/T56184 , because Treeviews and similar tools are going to need to be updated alongside the new pageview source data. What would be the best way to do this?