Sometimes you would likes to have split view. You can compare the codes at the same time on the same screen. So when switching tabs or buffer is not convenience to you, you can consider to open more split windows.
To open another windows, and lead you to current directory for file selection, you can do this.
Or you can open the same file in another windows by pressing Ctrl-w s
To move between different windows, press Ctrl-w arrow keys.
For more information regarding windows splitting, type