Eclipse underscore not visible

Problem:

Underscore is not Visibile on Ubuntu

With: Eclise Luna SR2, Mars 2, Neon 1a on Ubuntu 16.04 LTS

After few tests I understand this  is because my Ubuntu has text scaling factor set to 1.05 (from Unity Tweak Tool)

Solution #1

text scaling factor set to 1.00, but for me is too small
(you need to restart eclipse to see changes when you change Ubuntu text scaling factor)

Solution #2

change only the default font in Eclipse with Liberation Mono (text scaling factor set to 1.05 as default)
(for me the best solution at the moment, good font, good size, system text scaling factor set to 1.05 is good also for other applications like terminal)