Extends the default autocomplete to find matches in all open files.
By default Sublime only considers words found in the current file.
If you have Package Control installed in Sublime just press ctrl+shift+p (Windows, Linux) or cmd+shift+p (OS X) to open the Command Pallete. Start typing 'install' to select 'Package Control: Install Package', then search for AllAutocomplete and select it. That's it.
You can also install this package manually by entering the Packages directory of Sublime Text 2 and issuing on a terminal:
git clone https://github.com/alienhard/SublimeAllAutocomplete