When using the fluxus scratchpad, the idea is that you only need the one window to build scripts, or play live. f5 is the key that runs the script when you are ready. Selecting some text (using shift) and pressing f5 will execute the selected text only. This is handy for reevaluating functions without running the whole script each time.
The camera is controlled by moving the mouse and pressing mouse buttons.
The script editor allows you to edit 9 scripts simultaneously by using workspaces. To switch workspaces, use ctrl+number key. Only one can be run at once though, hitting f5 will execute the currently active workspace script. Scripts in different workspaces can be saved to different files, by using the (save-name) call in the different workspaces (see below).
If you press ctrl and 0, instead of getting another script workspace, you will be presented with a Read Evaluate Print Loop interpreter, or repl for short. This is really just an interactive interpreter similar to the commandline, where you can enter scheme code for immediate evaluation. This code is evaluated in the same interpreter as the other scripts, so you can use the repl to debug or inspect global variables and functions they define. This window is also where error reporting is printed, along with the terminal window you started fluxus from.