Question: I'm new to jedit, and I haven't yet found out how to open a new window. For example, I want to be editing one set of files in one space on my Mac, and edit a different set of files in another. Does anyone know how to open a new instance/window of jedit to make this possible?

Thanks

Answer: 
You should set **Buffer Sets** scope to "**View**"

See also: [Buffer Sets](http://www.jedit.org/users-guide/buffersets.html)
It is possible to really Open a new instance of jEdit, and not only to open a new set of buffers in the same instance. 

You have to launch jEdit with the -noserver option.
"Do not attempt to connect to a running edit server, and do not start one either."

Please see documentation here : 
<http://www.jedit.org/users-guide/cli-usage.html#d0e471>

On Windows, to set this option you have to add it to the command line of the shortcut which launches jEdit.