This option will split the editor into to editors.

Both editors work on the same source code.

What you change in one editor, you will change in the other editor.

 

Why is this useful ?

Some times you want to edit some code while looking at other code.

You can show some code you want to watch in the top editor and edit other text in the bottom editor.

 

 

 

 

If you select Split View again, the editor will return to it's normal state.