Theme breaks control box in application (JUCE)

[temrix]

• the GNOME/GTK version that is on your system
  3.22.11-0ubuntu3
• which Linux distribution you are running
  Ubuntu 17.04
• the version of Paper you are using
  2.1+r265dailyubuntu17.04.1

Most importantly: please attach a screenshot of your issue, a visual bug needs to be seen
I can’t attach a screenshot because I have already accepted the policies and therefore don’t get to see it anymore.

The theme breaks a control box in an application called Projucer (JUCE Homepage, GitHub repo).

When the user logs into their account, they cannot proceed because the privacy policies cannot be accepted. However, it perfectly works without the theme. I have already filed a report in the JUCE forum. See there or here for the dependencies of JUCE that may be relevant.