Missing icon in systray

[spacepenguin]

There is a better way ;-)
Change these 2 files:
/usr/share/applications/dropbox.desktop (this one with sudo)
~/.config/autostart/dropbox.desktop

In them find the line starting with Exec and change it to: dbus-launch dropbox start (delete the -i at the end as well)
That way, until you upgrade the dropbox package (which I do like never), it will stay unchanged.

I don't see the need to alter system files. You can alter the dropbox command via kmenueditor and it will create an own launcher for your user. And you can disable the  autostart of dropbox and create a new autostart for it with a different name. So no update will interfere with it.