ShellCorona provides a new DBus method "activateLauncherMenu". If that
is invoked it will look through all panels for an applet which has
X-Plasma-Provides with org.kde.plasma.launchermenu. If that also has
a global shortuct it gets activated and no further applet is searched.
The idea behind this DBus call is to provide a way to KWin to activate
the main appliction launcher when the Meta key is pressed.