Comment # 19 on bug 1123424 from Stefan Hundhammer

tux@g1:~> xrdb -query | grep Xft
Xft.dpi:    120.9599609375
Xft.antialias:    1
Xft.hinting:    1
Xft.hintstyle:    hintslight
Xft.rgba:    none

tux@g1:~> QT_LOGGING_RULES=qt.qpa.screen.debug=true qdirstat .
Logging to /tmp/qdirstat-tux/qdirstat.log

tux@g1:~> fgrep '<Verbose>' /tmp/qdirstat-tux/qdirstat.log 
2019-03-04 17:36:58.204 [2558] <Verbose> Failed to parse EDID data for output
"XWAYLAND0" edid data:  ""

2019-03-04 17:36:58.208 [2558] <Verbose> adding QXcbScreen(0x5596f81fc8b0,
name="XWAYLAND0", geometry=1680x1050+0+0, availableGeometry=1680x1016+0+34,
devicePixelRatio=1.0, logicalDpi=QPair(inf,inf), physicalSize=0.0x0.0mm,
screenNumber=0, virtualSize=1680x1050 (1680.0x1050.0mm),
orientation=Qt::LandscapeOrientation, depth=24, refreshRate=59.0, root=38c,
windowManagerName="GNOME Shell") (Primary: true )

2019-03-04 17:36:58.208 [2558] <Verbose> primary output is "XWAYLAND0"