smart inline editing & sub-buffers

The best sample I know is this from Adobe Brackets: http://blogs.adobe.com/jnack/2012/10/get-started-in-adobes-open-source-html-editor-brackets.html

For this a "sub-buffer" or "sub-window" would be necessary, that permit to edit another file from within the current one. 

This could lead to a large number of interesting plugins that permit to jump among interconnected files (definitions+implementations, html+css, views+controllers, etc)

Thanks,

Diego