- TLDR: we were scaling twice, resulting in ginourmous pixel values
The long story:
- since Qt treats the various scale factors in a multiplicative way (see
https://www.qt.io/blog/2016/01/26/high-dpi-support-in-qt-5-6 for
explanation) and there's no way to get the screen's baseline scale
factor programatically, we also have to export `QT_SCREEN_SCALE_FACTORS`
to something that's not equal to `0` or `1` to force the monitor scale
factor to `100%` and then compensate for it when exporting our own scale
value using `QT_SCALE_FACTOR`
- make the UI slider values go in `25%` steps, allowing for more fine
grained control; with `100%` we fallback to the Qt's native handling of
highdpi
- raised the maximum to `300%` since on highres displays, one wouldn't
be able to go over the implicit maximum of `200%` (due to the internal
scaling being 2x)
- scale our main window's minimum width/height so that we don't overflow
the monitor's available space
- modernize the `ConfirmAppRestartModal` to use `StatusDialog`
- use the new `Utils.restartApplication()` when changing the UI language
as well
- remove some dead code
In the (very) long term, we should take a different approach of scaling
our app independently of Qt, just taking the monitor
`Screen.devicePixelRatio` into account, similar to what other apps like
Telegram do
Fixes#13484
630da7caaa