Hmm. It doesn’t work. I see the icon when i do

dropbox stop
dropbox start

but I cannot click on it.

Installed nemo-dropbox. At least now I have “Copy dropbox link” command in menu. Don’t forget to do

$ killall nemo

after installation to make it work.

Final Solution

source 

Use

dropbox stop && dbus-launch dropbox start

Or

Do: opening ‘Preferences’ -> ‘Startup Applications’ and editing the dropbox entry so the command now reads:

CODE: SELECT ALL

dbus-launch dropbox start

update might overwrite the change. I think it’s better to leave the existing entry alone (only disabled) and create a new entry (e.g. “Launch DropBox”) with the new start command (dbus-launch dropbox start)