If you ever have a power outtage, hard drive failure, or similar catastrophic event on your system in the middle of editing a file like that on a remote system it may seem like all is lost.
However all is not lost if you've been saving as you go along.
Filezilla downloads the file into your temp folder before opening it in an editing application registered for the view/edit option, it works on that file & doesn't re-upload it untill the application closes the file.
When the application closes the file, the file is checked for changes & if it's changed you are prompted to re-upload that file & the temp file is deleted.
However, if you have a catastrophic failure before the application closes, that file is never re-uploaded which kinda sucks, but the good news is it's not deleted either.
So if you have a catastrophic failure in the middle of editing a remote file opened through "view/edit" in Filezilla, take a look in your temp folder before you open Filezilla again, your file should be in there.
An example of your temp folder on WinXP or Win2K is as follows, note that you'll need to have "hidden files and folders" visible to see the folder.
C:\Documents And Settings\Your Name\Local Settings\Temp\