DBUS Controls Plasma

Toggle Plasma DashBoard (Bring Plasmoids to front)

dbus-send --type=method_call --dest=org.kde.plasma /MainApplication local.PlasmaApp.toggleDashboard

Lock the Desktop (Turn on ScreenSaver and require password)

dbus-send --type=method_call --dest=org.freedesktop.ScreenSaver /ScreenSaver org.freedesktop.ScreenSaver.Lock