I am using Visual Studio 2013 and I want to show all the function prototypes that I have in a file at one glance!
Just promoting my comment to an answer:
you can try extensions like:
Im using it happily for years with different technologies. The only drawback is that it takes a bit to map with huge files.
Alternative is just a class view (ctrl+W,C) panel in Visual Studio, but it's still poor, not very configurable and doesn't show much.