Feature summary (what you would like to be able to do and where):
On wikisource, the new extension edit-in-sequence (Documentation) have a toolbar displayed at the top of the page. This bar should stick to the top of the screen to be always visible even if you scroll down (same way as the edition toolbar works with the VisualEditor).

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):
For now, every time you want to save a page after correction using that tool, you have to scroll back up to have access to the save button. It's not ergonomic and make lost a lot of time. Having the bar following us during scroll would me more practical.

Benefits (why should this be implemented?):
This would improve usability of this extension as it allow to save a page without having to scroll back up after correction.