Get Qt5 Apps To Use Native Gtk+ Style In Ubuntu 18.04 LTS

Some Qt5 applications don’t use a Gtk+ style by default in Gnome (in Ubuntu 18.04 for example), which makes them look out of place. This includes applications like VirtualBox, VLC, qBittorrent, Simple Screen Recoder, the ownCloud desktop client, and so on. This article explains how to fix this and get Qt5 applications to use a Gtk+ 2 style in Ubuntu.