edit multiple files in one "pane"

Currently, each window can have multiple panes depending on your layout settings. However, when you work on e.g. a large client- and server-side javascript project, you can easily have many related files open in tabs in each pane that you need to switch between fairly often. Goto Anything is ok, but it's not as fast or as easy to work in as if some of the files were rendered into one composite file. I think this is because it is easier for me to remember which code point I need to find and use the Find feature than to remember which file it is in and use Goto Anything, unless I'm misunderstanding how to use Goto Anything. Sometimes it's even faster to just use the mouse to pick the right tab than to try with ctrl+tab (I would prefer tab-order to time-order or whatever the current ordering is) or type the file name in Goto Anything.

So, what I'd really want is something that takes a bunch of separate files and presents them as one file, with collapsible/reorderable boundaries between files. This happens to have a side effect of making it easy to have one file with multiple different syntax highlighting and other language-specific features. I imagine it could be implemented as something like a pre-processor where I specify a config file with all the different groupings (and maybe also stuff like strings to prepend and append to each file). Ideally I could also take the same config file and output the composited files to the file system like make or other build process tools.

Other than that, I love Sublime. Keep up the great work!