Use to work on two parts of a program, or two programs,
simultaneously.
 
Split divides the View window horizontally. Use F6 and
SHIFT+F6 to move between the windows on the screen:
  - F6 moves the cursor down through the windows.
  - SHIFT+F6 moves the cursor up.
 
To restore an unsplit View window, choose Split again.
 
The active window contains the cursor. This window can be
sized from the keyboard:
 
  - ALT+PLUS(+)  expands it one line
  - ALT+MINUS(-) shrinks it one line
  - CTRL+F10     expands it to fill the screen, or returns
                 it to its former size