Leopard Spaces

I recently installed Mac OS X Leopard on my MacBook. I like it so far, but I think an opportunity was missed. I like Spaces, which allows you to have virtual desktops to make things more uncluttered. However, when you add an external display, each virtual desktop increases in size to add that extra real estate. What would have been nice (in my opinion) would have been to realise two of the virtual desktops - one on the laptop, one on the additional display. That way, if I moved stuff to the external display, when I disconnect the display, instead of moving those windows to my local display, thus recluttering it, they just sit in the virtual space. Maybe that's a relatively unusual way of doing it - after all, I am guessing it's a small portion of users that would use a laptop with an external display in such a manner on a regular basis. Still, the option would have been nice.