[Interest] Qt Docker images for Windows

[Richard Weickelt]

> TL;DR: I created a Windows Docker image containing with Qt open-source
> installations at https://hub.docker.com/r/keneanung/qt-windows
> 
> After some research, I didn't find any images for Windows that
> included Qt, the preferred method seems to be cross-compiling, and
> thus I created a version for ourselves to use.

Thanks for sharing.

We ran into a similar issue in the Qbs repo. The main pain point is the Qt
installer which provides very poor user experience in a headless
environment: https://bugreports.qt.io/browse/QTIFW-166 and
https://bugreports.qt.io/browse/QTIFW-1361

I did the same: compile Qt in a Docker environment. But it's very
time-consuming, needs to be maintained and we faced issues when running
testcases with gcc's address sanitizer enabled (on Linux). Windows
containers on Windows showed poor performance on Travis CI and their size is
tremenduous. And what to do on Mac OS which doesn't support container
virtualization?

Eventually I ended up writing a small shell script that pulls and extracts
the needed Qt packages directly from
https://download.qt.io/online/qtsdkrepository/ on any platform. That is much
faster and way more flexible than the official Qt installer. We still use
Docker in our CI, but only on Linux where it gives us the most benefit.

The script can be found here:
https://code.qt.io/cgit/qbs/qbs.git/tree/scripts/install-qt.sh

Richard