Especially prevent certain elements from expanding (the additional space between the elements looks weird).
* Lazy initialize systemd interface and don't initialize it at all if the unit name is empty * Allow to supervise/control system-wide units in addition to user units (see https://github.com/Martchus/syncthingtray/issues/61) * Avoid redundant code
So settings pages, web view and other widgets can be used in other components such as the Dolphin plugin and Plasmoid, too.