external QtHelp browser (was Re: undocking/detaching toolviews to regular windows instead of tool windows)

I've been working on a complement/alternative to using the embedded documentation toolview with standalone windows. Those are nice, but what I have really been hoping for is a (QtHelp) documentation browser like Qt's Assistant (the one in Qt Creator is even nicer but not standalone).

This patch gives me such a feature: https://phabricator.kde.org/D4484 . With that in place, I don't even have to add the Documentation toolview to a toolbar. Clicking on the "Show documentation for" link in help context popups will show the documentation in question in the Assistant.

Last paragraph in the latest update message of D4484:
As argued before, I see this as a good complement to an embedded documentation viewer that's based on QTextBrowser, a step beyond what's possible with a floating embedded doc viewer, even if it uses regular windows. Qt's Assistant supports having multiple tabs open for instance, has better search and filtering facilities, and can host a centralised (shared) collection of QHC documentation from various locations, accessible without having to start KDevelop (or add them in KDevelop too).