I really love the way sublime handles the pane splitting.
- Combining when reducing the number of panes
- Making it possible to reduce the number of panes without have to close all tabs in it
- Making a pane persist even when there’s no tabs open in it
- Not just open the current file twice when splitting (that’s the least likely behavior someone would want)
- Handling splitting at a higher level than files. In sublime for example, cmd-3 splits the screen in 3 panes, the new ones having nothing opened. That way it’s easy to drag some tabs over, open a new tab there, etc.