List of steps to reproduce (step by step, including full links if applicable):
- Switch to horizontal mode while editing a page in Page: namespace in Wikisource using the "Proofread tools" -> "Vertical/horizontal layout" icon
What happens?:
The edit window remains half-screen width, leaving the right-half as a blue empty square
What should have happened instead?:
The edit window should be full-screen width to effectively use whole screen in edit mode.
Software version (if not a Wikimedia wiki), browser information, screenshots, other information, etc:
MediaWiki 1.38.0-wmf.12 (rMW9574ef2738c8), tested on FF but this probably does not matter.