As reported at https://meta.wikimedia.org/wiki/Talk:Community_Wishlist_Survey_2021/Real_Time_Preview_for_Wikitext#Wrong_preview_on_table
In order to get a live preview of wide tables etc. it would be useful to be able to have a wider live-preview pane, positioned below (or above) the text edit area.
This would be similar to the to ProofreadPage feature which swaps the proofreading pane from side to top.
This feature would be wonderful to see! What steps would need to happen to incorporate it? I'm new to Phabricator and I would love to know if there's any way to help.
Switching the panes around probably involves setting flex-direction:column on .ext-WikiEditor-twopanes-TwoPaneLayout and fixing up the direction of the dragbar and widths of the other panes. But I think the first question is how the switch should happen — I guess the simplest is a new button next to the preview-reload button in the toolbar. Is that too prominent? Perhaps it should be an opt-in feature, at least to start with, to avoid cluttering up the toolbar.
Just out of interest, what are your reasons for wanting this?