Your comments

I also recommend checking out this plugin that I wrote:

It makes it easy to make arbitrary pane layouts.

There are keyboard shortcuts to move files to different pane numbers, but no shortcuts to move them, say, right a pane. I don't think doing this is actually possible at the moment, because while you can set arbitrary layouts I believe there's still no way to read back what the current layout is.

If you check out your Main.sublime-menu you can see how the layouts are actually created.

It already supports arbitrary layouts; it's just missing the split commands to generate them.
Unfortunately, none of these apply to what he's talking about. He wants spaces to act as tabs when using the arrow keys to move through his text.
Could it be changed to show the *last* keybinding instead? I feel that in general the last one is the one you want (because it's probably the one that you put in your user keymap).
Add this to your user file settings:
"highlight_line": true,