Gigantic fonts makes log-in window unusable on Linux

[splodgenik]

Using Debian 9 64-bit on Intel Broadwell Iris the login/create account windows are unreadable due to the text coming out gigantic (button labels are ok, everything else is huge as you can see in the screenshots (well, window-shots) below). My native resolution is 2560x1440, starting at lower resolutions makes the text less disproportionately huge but still too big to use - it's still oversized running at 640x480.

It seems to be scaling up the text size to account for screen size but getting the calculation wrong. Any debugging suggestions, or tweaks so I can get the game running even if we can't find the root cause?

Thanks.

 

[splodgenik]

This turns out to have been some weird X11/Qt4 thing affecting all Qt4 applications that went away when I restarted Xorg, sorry for the misplaced bug report.