OK, I know this is a necro post but I’ve been researching this for a few Qt (4 & 5) programs so I’d appreciate finding this in a search.
What definitely works (at least in Ubuntu 16.04):
- Install Qt5 style plugins—sudo apt install qt5-style-plugins
- Copy /usr/share/applications/calibre.desktop to ~/.local/share/applications/calibre.desktop
- Edit the copy and change the Exec= line to Exec=env QT_STYLE_OVERRIDE='gtk' calibre
- Use this to launch calibre, i.e. either drag it to the launcher or make it executable and double-click it.
You should also be able to put
QT_STYLE_OVERRIDE='gtk' into your
/etc/environment file to do it for all Qt5 programs, but I haven‘t tested this.
More info: