Clarification on screen geometry and HiDPI

Hi all,
I'm trying to understand
QScreen::geometry
in a Linux/X11/Plasma HiDPI desktop set up, and would appreciate some help in understanding those values.For example, I have two screens:
 DP1: 1920x1080, left
 eDP1: 3200x1800, right
As X11 does not allow different scale factors for screens, I have a global scale factor of 2.
The Plasma desktop environment also sets the following environment variables:
QT_SCREEN_SCALE_FACTORS=eDP1=2;DP1=2;DP2=2;
QT_AUTO_SCREEN_SCALE_FACTOR=0
Qt reports the screen geometry as follows (excerpt from
qtdiag
):Screens: 2, High DPI scaling: active # 0 "eDP1" Depth: 24 Primary: yes Geometry: 1600x900+1920+0 (native: 3200x1800+1920+0) Available: 1600x900+1920+0 Virtual geometry: 3520x900+0+0 Available: 3520x900+0+0 2 virtual siblings High DPI scaling factor: 2 DevicePixelRatio: 2 Pixel density: 1 Primary orientation: 2 Orientation: 2 Native orientation: 0 OrientationUpdateMask: 0 # 1 "DP1" Depth: 24 Primary: no Geometry: 960x540+0+0 (native: 1920x1080+0+0) Available: 960x540+0+0 Virtual geometry: 3520x900+0+0 Available: 3520x900+0+0 2 virtual siblings High DPI scaling factor: 2 DevicePixelRatio: 2 Pixel density: 1 Primary orientation: 2 Orientation: 2 Native orientation: 0 OrientationUpdateMask: 0
And there are multiple strange things that I fail to understand:

The geometry of eDP1 seems wrong  it has an x offset of 1920, but why isn't this number scaled accordingly? As far as I understand this geometry value should be a "logical" one, which means in a "logical" space the eDP1 screen, being right of DP1, should be positioned at +960+0.

The available virtual geometry does not make sense at all  It seems the width of "3520" is just an addition of 1920 and 1600, which are a scaled value and an unscaled one.
I'm using Qt 5.15.0. Any help is greatly appreciated.

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