tag-restricted bug list browsing

The task-relevance of bug listings can be greatly improved if it were possible to /easily/ and /incrementally/ restrict displayed bugs using tags.

For example, at the moment https://launchpad.net/products/launchpad-bazaar/+bugs gives me a nice focused list of the issues I need to worry about. Then tags allow me to restrict this listing further. https://launchpad.net/products/launchpad-bazaar/+bugs?field.tag=ui gives me all the UI issues I need to worry about.

If we merge all launchpad sub-products, and use tags to mark bugs belonging to one sub-project, I want to keep this level of functionality: from the list of bugs associated to a tag, I want to be able to display, in ONE click, the list of bugs associated to this tag AND another (as in logical AND).

In the same spirit, I do not want that the tag list my normal bug listing page be cluttered with all the tags I need not to worry about, like those related to soyuz or rosetta subsystems. That could probably be achieved by not displaying tags that are used by no bugs in the current tag-restricted listing.

In the unrestricted bug listing, something is also needed to keep the tag list task-relevant. Only showing the most used tags might sound like a good idea, but it means that a tag that is important to ME would end up not being displayed just because tags I do not care about are used more frequently in other Launchpad sub-projects.

One way of improving task-relevance of the tag list in unrestricted bug listing would be allowing users to define per-project (project/product/distro) lists of favorite tags. Since my focus is mainly vertical (launchpad-bazaar integration), my list would include highly specific "vertical" tags (launchpad-bazaar and each of its subsystems) and some generic "transverse" tags (oops, ui, xmlrpc).