If you use large screen resolution, as WQHD or 4K monitor, you can now use until 512x512 px size for thumbnails.
When this option is turned on/off from setings panel, user need to restart digiKam to take effect, and thumbnails
need to be rebuild over collection through MAntenance tool, to update digiKam thumbs database.
BUGS: 328430
FIXED-IN : 4.1.0