Icon missing from System Tray

[silverback]

An Icon (Dropbox) has gone missing from my System Tray. I can see it if I click on the "Show Hidden Icons" up-arrow.
Any ideas on why this has gone missing and how can I restore it to permanent view?
Thanks
Silverback

[HansV]

Click the 'Show Hidden Icons' arrow.
Try dragging the Dropbox icon out of the hidden icons popup to just to the right of the 'Show Hidden Icons' arrow and drop it there.

[silverback]

Brilliant. Worked a treat.
Many thanks.
Silverback