Also, this feature will likely be no longer available when we switch to Qt 5 because they ditched QtWebKit (and a few more modules that we use in QMC2). I can't say yet if the new QWebEngine API and its support for JavaScript is equivalent enough to what QtWebKit supports (AFAIK, it's not a 100% replacement yet) so that the feature could be ported, but if not, it may get dropped anyway, and be replaced by something similar in the future.

That's also a reason why I don't pay too much attention to this MSYS2/MinGW specific problem. The solution could be to create a local Qt 4.8.7, but that's your own job.

A mind is like a parachute. It doesn't work unless it's open. [Frank Zappa]