per sketch persistency of Board/Programmer

I'm working on I²C master (Uno) and slave (Tiny85) and thus have two or three sketches open all the time (Master, Slave and, sometimes, the ISP). Obviously, those sketches are all written to their specific platform (Master uses Wire while Slave uses TinyWireS etc).
It would be extremely handy if the board and programmer settings (along with the com port settings I suppose) could be set persistently for the specific sketch window, so that whenever I compile the Slave, it does compile for Tiny85 and I don't have to go into the board menu whenever I switch sketches between M and S.

You can do that by starting multiple instances of the IDE, instead of multiple windows in one instance.