Currently, the "Shown when relevant" visibility option in the system
tray shows an icon iff at least one vault exists, regardless of open
status (i.e., if it is open or closed). Change this behavior to show an
icon iff at least one *open* vault exists, allowing the user to be more
mindful of potentially sensitive information being accessible.
The previous behavior can be emulated by selecting the "Always shown"
visibility option, assuming that the user does not create and delete
Plasma Vaults for recreation.