How do I switch between two notebook windows in the Mathematica 9 interface?
I would like to use a keyboard shortcut such as Ctrl+Tab or Alt+ Tab as with windows or tabs in programs like Firefox.
If you're on a Mac, the default is usually CMD + ` . You can remap the keyboard shortcuts via the links in Öskå's comment above.
FWIW, you can also create your own palette using the
Button command and then install it in Mathematica via the Palette menu; this is useful if you have a variety of actions you want to take, for example, rearranging / resizing windows, restyling cells, ...