On the Mac it's possible to drag items from a window without focusing it first. This would be a handy feature for file management in GNOME, especially with Nautilus where the sidebar isn't a valid drop target for files. Currently, dragging files from a partly occluded window brings that window to the front -- this sometimes makes DnD more awkward than it needs to be.
I think you can do this now if you change the setting in your sawfish keybindings to not raise the window but to pass through the click anyway. I am not sure all of us are convinced this is the best way to go for our setup - but thankyou.