9. In a digital medium environment for synchronized editing of simultaneously displayed first and second documents in a user interface, a method implemented by one or more computing devices comprising: opening and displaying the first document and the second document simultaneously in the user interface; outputting the first and second documents in the user interface that is configured to support editing of at least the first document; receiving an input via the user interface to edit a first portion of the first document corresponding to a first portion of the second document; subsequent to receiving the input to edit the first portion of the first document, receiving an input via the user interface to edit a next sequential portion of the first document relative to the first portion of the first document; and responsive to receiving the input to edit the next sequential portion of the first document, changing a visual characteristic of a next sequential portion of the second document relative to the first portion of the second document automatically and without user intervention in the user interface and forming a correspondence between the next sequential portion of the first document to the next sequential portion of the second document.
9. In a digital medium environment for synchronized editing of simultaneously displayed first and second documents in a user interface, a method implemented by one or more computing devices comprising: opening and displaying the first document and the second document simultaneously in the user interface; outputting the first and second documents in the user interface that is configured to support editing of at least the first document; receiving an input via the user interface to edit a first portion of the first document corresponding to a first portion of the second document; subsequent to receiving the input to edit the first portion of the first document, receiving an input via the user interface to edit a next sequential portion of the first document relative to the first portion of the first document; and responsive to receiving the input to edit the next sequential portion of the first document, changing a visual characteristic of a next sequential portion of the second document relative to the first portion of the second document automatically and without user intervention in the user interface and forming a correspondence between the next sequential portion of the first document to the next sequential portion of the second document. 12. A method as described in claim 9 , wherein the changing provides focus to the next sequential portion of the second document.