Interesting idea. Don't think it's been done with an IDE before. Expanding code based on context would be cool too. (eg. second column shows the implementation of whatever the first column's cursor is on - super handy when stepping through code)

Huh, that's interesting. I can't say I've encountered that need before though; it's much more valuable for me to have many panes of different files open at the same time (or two locations of one file), rather than an "extended buffer" of a single file. Most of the context outside the immediate method is not immediately important, and most methods are just a few lines long -- enough to fit in a pane.

No, it creates an additional editor area that can have any number of files open in it. You drag files between the areas or open the same file in multiple areas.

You can continue splitting any area vertically or horizontally to create a configuration that fits your working style or the code you're currently writing.

You can drag and drop but it's a bit picky - grab the file tab and drop it in the other pane's tabstrip.

Definitely something that could be improved (as well as splitting to two panes gives you 2 panes of the same file..)

The drag and drop works but it's a bit weird. You have to drag the tab into the other editor window, not on the tab bar.