copy window regions

I am working on making a cheesy app that will copy a clip the minimap from a slave and put it on the main (for gathering and question), essentially copy window regions x,y-x,y to x,y and put that small snippet into another window that is always on top and has no decorations. Not so bad looking with the square minimap windows on the slaves.

Essentially its a read-only vnc redisplay of just those specified regions, I am sure there is some spiffy directx method.

This would be similar to HKN stacking windows and removing regions in the foreground to show the background (and moving the background minimap to be shown through the hole).

Any ideas? Right now I have it slow the polling after I press any of a list of keys (eg, if i am in combat) and after that I really cannot notice anything impacting me, though I can tell that the nodes that flash for just a moment on the far edges of the minimap on the slave often never 'appear' due to polling, eh.