Video is not scaled properly when Qt5 HiDPI scaling is in effect
On Fedora 25 running vlc-3.0.0-15.20161221git634cd2e0.fc25.x86_64 I'm seeing an issue where the video is not scaled properly in either a window or fullscreen. The video appears shrunken and placed in one corner. To workaround the issue I can set the environment variable QT_AUTO_SCREEN_SCALE_FACTOR=0 which disables auto HiDPI support in Qt5. The other option is to leave auto HiDPI support on (which gives a 2x increase) and set QT_SCALE_FACTOR=0.5 which effectively provides a scaling of 1x again.