Context: Ubuntu 11.10, Unity

Let's say I have a screen at resolution 1000x500.

What I'd like to do is split the screen down the middle so [Unity or X or ?] acts as if there are two displays (each of 500x500).

Examples:

• Unity will display a different toolbar (the top one) on each side of the display.
• If I maximize a window on the left side of the screen, it will fill the left side only.
• If I maximize on the right, it will fill the right.
• If I hit "fullscreen" in youtube (flash) or Chrome or Movie Player, it will only fill the side of the display that it's on.

If it's really is impossible to do this with Unity, will it work with Gnome3 and how?

A million thanks!