On my laptop with 1920x1080 display the Preferences dialog does not fit vertically in the screen:
OS: Windows 8.1
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.18.15694 (Git)
Build type: Release
Branch: master
Hash: 96dee91d5e7d7fd37f43a4dcf406a120ae1f1b8a
Python version: 3.6.6
Qt version: 5.6.2
Coin version: 4.0.0a
OCC version: 7.3.0
Locale: Bulgarian/Bulgaria (bg_BG)
It is possible to resize it horizontally down to some fixed size but the vertical size always makes it bigger than the screen. So the Ok/Cancel/Apply buttons are almost not visible. Is it some limitation to the dialog, a hard coded minimal height or just some setting that I am missing?