I was playing with app-crypt/yubikey-manager-qt-0.3.1 today, but it installed without requiring dev-qt/qtquickcontrols[widgets] that it needs apparently. So when run: $ /usr/bin/ykman-gui QQmlApplicationEngine failed to load component qrc:///qml/main.qml:4 module "QtQuick.Dialogs" is not installed qrc:///qml/main.qml:2 module "QtQuick.Controls" is not installed qrc:///qml/main.qml:4 module "QtQuick.Dialogs" is not installed qrc:///qml/main.qml:2 module "QtQuick.Controls" is not installed ^C Emerging dev-qt/qtquickcontrols-5.7.1 fixed the issue (USE=widgets is default?).
Thanks, fixed in 0.3.2