Web IDE Editor Improvements [Panes and Preview]

Problem to solve

Limitation of utilizing the entire screen real-estate for a single file, as well as making the user have to flip back and forth between the Edit and Preview panes. Allow editors to work on multiple files at once while in the editor view, as well as provide realtime preview of Markdown and reStructuredText documents.

Intended users

Any developers or users that find the need to edit multiple files at once or see the changes they are making who feel it's faster to do it from the Web IDE and don't want to make syntax errors.

Further details

Enhance the capabilities of the IDE to introduce fairly common basic functionality found in most client side editors and some cloud ones.

Proposal

Introduce the ability to work on multiple files simultaneously in the Web IDE, either through vertical splits or something as simple as a dual pane editing mode. It would also be great if the Preview functionality could be handled in a tab of a separate pane (similar to the way VSCode works when choosing to preview a Markdown or reStructuredText file) so that users editing markup files would have the ability to see the results of their edits. This could help reduce accidental syntactical errors that could possibly require a follow-up commit.

These kinds of functionality would make the Web IDE a good alternative to make quick edits to multiple files while on the go or for users that catch something while browsing source without needing to make the edits locally then pushing them up.

Permissions and Security

Documentation

Descriptions of the features and how to use them would need to be added here: https://docs.gitlab.com/ee/user/project/repository/web_editor.html

Testing

What does success look like, and how can we measure that?

Links / references