List of steps to reproduce (step by step, including full links if applicable):

• zoom of your page should be 100%
• log-in in with the skin Legacy Vector
• open a page in edit mode for exemple this page
• on the editing toolbar, click on "Proofread tools", then on the icon "Vertical/horizontal layout" to obtain the vertical mode

What happens?:

• with a wide screen, the window on the bottom with the text to edit is heigher then the window on the top with the image of the text, which hinders the work of editors

What should have happened instead?:
2 hypothesis:

• the two windows in vertical mode should have the same height
• a better solution should be to allow customization of the size of windows, "resize: vertical" for textarea

Software version (skip for WMF-hosted wikis like Wikipedia):

Other information (browser name/version, screenshots, etc.):
A user notice it is a regression, he said once it was possible to customize the height of the windows. (See also T38230)
Discussions: 1 and 2

Images:
Legacy Vector - editing in vertical mode, 1366x768 screen
Vector 2022 - editing in vertical mode, 1366x768 screen
Legacy Vector - editing in vertical mode, 2560x1440 screen
Vector 2022 - edit in vertical mode, 2560x1440 screen