Nope MxxCon, I'm exactly writing about Ctrl-E
When you choose to edit a file, flashfxp downloads the file to a temp dir and then opens it using the internal editor or the editor you have configured for the extension of the file.
Suppose you want to edit a .html file, previously associated to notepad. So, select file, press Ctrl+E, the file are downloaded to a temp dir, notepad.exe are executed and the file is opened.
Now, how many times you can see the results of your editing?? Just one, because you can save the file a thousand times in the temp dir but it will uploaded back to the server just one time. So, I think rdone wrote about a feature that allow to upload a file each time is saved, so e.g. you can view the big mess you are doing to the web page... as the editor remains open, you'll always have the chance to press the magic Ctrl-Z key