The palette can be shrinked by the 'Hide Palette' option. It would be very useful to have that option in other windows as well. E.g. to hide the Model Window in the same way. In larger views I like to have the option to enlarge the size of the view-window as much as possible, so to easily shrink and enlarge the other windows.
Or am I missing a simple option which Archi already has?
Every panel (ie. internal window) in Archi can be shown/hidden from the window menu. In addition, you can always maximise a panel by double-clicking on its name.
Have a look at the user manual where all this is described.