Feature summary (what you would like to be able to do and where):
createonly= would be similar to redlink= but would deactivate the submit button, turn the input's border red and display a notice below when the page already exists.

Use case(s) (list the steps that you performed to discover that problem, and describe the actual underlying problem which you want to solve. Do not describe only a solution):
Currently, when the page already exists, instead of the preload page, the actual page content is loaded into the editor, which is not always what you want and can confuse users

Benefits (why should this be implemented?):

• Might improve usability/UX, because it clearly communicates
• User doesn't have to navigate back when they don't want to edit an existing page