What is the use of firebug's "Open With Editor" function?
I'd say it'll allow you to visualize a file / feed with an editor -- which means better searching features, syntax-highlighting, better-ability to copy code...
But it means you have to configure the editors, so firebug knows how to call one -- especially, so it knows how to pass it the data.
Edit after the comment : no, I don't see it allows you to see your modifications into the website -- but it's, I think, easier to go through the HTML code this way, with the editor you're using in your every-day life as a developer.
For example, you can check what's said in this article : Check Edit HTML Code with Firebug -- check the Editing With Firebug section.
And to use it, you have to :
- select something like "
Open with editor > Configure editors
", and, in the dialog box, set the path to your editor - and, then, to edit some HTML page, select "
Open with editor > name of your editor
"
(The labels may not be exactly those : I'm using the french version...)