GUI too small to be legible on 4k+ DPI monitors, does not scale like other ubuntu apps

MKVToolNix GUI v15.0.0

Ubuntu 18.04.1 LTS 3840x2160 (16:9) resolution Dell XPS 15 Scale 200%

GUI is too small to be legible in 4k+ DPI monitors. Does not scale like other Ubuntu apps with global scale setting.

Note that titlebar is about 12 px font. Anything smaller is too small to read.