You can split the editor to view and edit different parts of a document at the same time.

Go to the CotEditor app
on your Mac.
Do one of the following:
Choose View > Split Editor.
Click the button on the right edge of the navigation bar.
To close a split editor, choose View > Close Split Editor, or click the Split Editor button on the left side of the navigation bar.
You can also change the split orientation by choosing View > Stack Editors Horizontally (or Vertically).