Opening OpenPGP Applet multiple times creates as many icons in the task bar
Until Tails 2.5, there was no OpenPGP applet launcher in the Applications menu. In Tails 2.6~rc1, there is one, and then, when opening OpenPGP Applet through Applications → Accessories → OpenPGP Applet it creates an icon in the task bar (top right). Where an OpenPGP Applet already exists by the way. And clicking x times creates x identical icons.
Hide OpenPGP Applet launcher from the Applications menu.
Until we have something (else than the systray icon) to launch, i.e. other bits
of #7433 are done, it makes no sense to have a launcher there in the context of
Tails, since we launch the applet by default, and added a confirmation dialog
for exiting it. And keeping the launcher around means that users will try
to run it more than once, which is not very well supported.
Note that we have to move the desktop file to /etc/xdg/autostart/:
both Hidden=true and OnlyShowIn= would not only hide the launcher,
but they would also inhibit the automatic startup of the applet.