Holding down the amiga key will only close the source window.There is also a comodity to do that automaticaly, somewhere in the depth of the aminet irc.
Go for Scalos or DOpus Magellan as Korodny wrote.
I'd go for Scalos. It's closer to Workbench compared to Dopus.
Dont know if Scalos 1.2 can do what you want but the 41.x versions can.
Take a look here...