Currently, the workaround to get LyX working with HiDPI is setting the
environment variable
QT_AUTO_SCREEN_SCALE_FACTOR=1
It seems that this solution isn't ideal because it applies to other
applications that don't work well with this setting. One example, I came
across is Dropbox. I noticed that the system tray icon was unresponsive,
so I re-installed Dropbox. But I couldn't log into Dropbox because the
login dialog was unreadable (too large for the window). Removing the
variable fixed this and the tray icon is working as expected too. But,
of course, LyX is not nice to use now.
Daniel
