but the systray applet is still missing and therefore I cannot scan for a network.
You can R-click a blank bit of the panel.
Add to panel...
Add what you'd like (systray
But network-mangler isn't currently as functional, or intuitive or smart as wicd
. Please try installing wicd
for wireless happiness.
That said, NM manages "mobile/cell phone" dongles better than wicd
currently does. So if you need to use one of these, reconsider.
Make your choice, or keep switching between them, depending on what connection you want to establish and how. Eventually, I expect this'll all be sorted out.