qmlglsink: Fix HDC for wglMakeCurrent() calls - enables multiple instances on Windows
This patch aims to fix issue discussed at #477 (closed)
There is one known issue - I did not update meson.build related to ext/qt. I'd kindly ask someone who has experience with meson and ability to test it on Windows to port my changes from qtplugin.pro into meson.build (just add user32.lib to link options).
Edited by Matthew Waters