Ubuntu 9.04 / T400 / DVI display resolution?

[Jaggie]

Hi!

I'm using Ubuntu 9.04 on T400 with Radeon HD3470 GPU and a proprietary fglrx driver installed (I guess, a friend of mine did the installation as I'm new to Linux...) and I have connected a WUXGA display to the DVI port of an Advanced Mini Dock I'm also using.

I'm able to use both mirrored and extended desktop with both displays set to 1440*900 (the T400's native resolution), but the full resolution of the external display (1920*1200) is missing from the list of available resolutions in both the GUI's Display Prefereneces and ATI Catalyst Control Center. How can I get it there?

I wouldn't actually even need the laptop's screen - the external display automatically working in the full resolution whenever I put the computer on the Dock and switch the power on would be a dream come true for me...

Thank you in advance for any answers!