If you stretch the main Cubase window across all your screens you can position the subwindows anywhere you want.
To drag windows outside of the Cubase window, they need to have 'always on top' enabled. This is available for the mixer, but I don't know about the project window and mediabay to be honest.
Software: Steinberg Cubase Artist 6.5.5 64-bit.
Hardware: HP elitebook 8530b with W7 Home 64-bit
Mackie Onyx 1620i - Steinberg Midex 8 - Steinberg CC121.
Analog: Alesis M1 - Behringer Powerplay Pro-XL - Studio Projects C3 - AKG K612Pro
Instruments: Yamaha DTX750k - Yamaha MO-6 - Waldorf Blofeld - Korg Wavedrum WDX.
3rd party plugins: Native Instruments Prism - Rob Papen Distort - Rob Papen DelayMy humble contributions to what could be considered music.