Emulator
The Emulator editor is used to start a new debug session for the current project, in the engine's Emulator. It's another kind of debugger Fighter Factory supports, but instead of being the native engine as a separate process, it runs inside the program, making real-time inspection of in-game variables and testing a lot faster and robust.
Debugging allows you to make the engine stop execution at points defined by breakpoints, so you can track bugs easely and faster.
Fighter Factory Studio doesn't come with a general purpose Emulator. This function is provided by the engine's module, so the available feature set is subject to change based on each engine implementation.
For more info about debugging, see Debug.
Workspace
The graphic workspace contains a screen clipped-region where sprites are rendered into and collision/hit boxes (Can be enabled/disabled in the View menu).
The zoom can be changed using the mouse wheel.
Keyboard keys can be used to send commands to the engine.
M.U.G.E.N.
See M.U.G.E.N Emulator.