Would it be enough to just move this message to the top, above the custom edit notices?

That would be better than nothing; and if it's easy enough to do while we are discussing better solutions, go for it. If it can also be given the same styling as with the 2010 interface (seems to come from classes mw-message-box mw-message-box-warning), that would also help. But the main problem is that the alerts disappear when you click anywhere else on the screen.

Proper solution to fix this once and for all (and to make other issues with content size differences go away) is T212848: Make edit notices more visible in Visual Editor, btw

Change 923695 had a related patch set uploaded (by Bartosz Dziewoński; author: Bartosz Dziewoński):

[mediawiki/core@master] Move "editingold" notice to the top, always add warning frame

https://gerrit.wikimedia.org/r/923695

What happens?:

editingold ("Warning: You are editing an out-of-date revision of this page. If you publish it, any changes made since this revision will be lost.") is hidden between the edit notices and the page protection info, in plain black-on-white text, in a narrow box that disappears if you click anywhere else on the page.

In the 2017 editor, sometimes at least revision-info is shown, but that just says that you're viewing an old revision. It says nothing about the fact that you're going to stomp over other users' edits

And in VE, there is no other indication that you're even viewing an old revision.

I took some time to work out what exactly happens and why, for QA purposes and for discussion. It seems that the revision-info message is usually shown in both VE and 2017WTE, except when you are using a single edit tab and you open the "edit" link in a new window (or follow an external link).

So for example, if you visit https://en.wikipedia.org/w/index.php?title=Donald_Trump&oldid=1155757842 and then click any of the edit links on the page, you will see that message, and the editingold notice, which look like this:

…in the classic 2010 wikitext editor:
…in the visual editor and the 2017 wikitext editor:

However, if you directly visit https://en.wikipedia.org/w/index.php?title=Donald_Trump&oldid=1155757842&action=edit, and you're using single edit tab and either VE or 2017WTE as your preferred/only editor, you will instead see only the unnoticeable editingold notice:

Why does this happen? Because the revision-info message is not a real edit notice, but instead it's inserted into the "subtitle" area (#contentSub), similar to e.g. the message about viewing a redirect. VE doesn't do anything with that message; it's displayed by either the MediaWiki view action, or the MediaWiki edit action, and preserved when VE takes over the page. But in single edit tab mode VE completely takes over the MediaWiki actions, and it doesn't display the message. You can recognize this by the unique message on the loading screen:

However, this behavior is completely unintended; no one has thought about how the various parts interact here, and decided to make this message appear or not appear in VE. It's just an accident that it shows up most of the time. The message itself is a bit broken in this context (e.g. the links are not clickable).

I'd like to fix it by making it a real edit notice (and merging it with the editingold edit notice), but that would have the drawback of pulling it into the popup menu, which might make it less noticeable than before, unless we also change the design for T212848. I think I'll just leave it unchanged for now, and just make the editingold message more prominent (see the patch I proposed).

(By the way, just look at all this text in the screenshots… ain't nobody reading all that. I had to resize the browser just to show the two messages I am describing. The notice about old revisions is not the only problem here. As long as there is just so much useless text, people will not read it, and will miss the important messages, even if – especially if! – we make them even bigger.)

(By the way, just look at all this text in the screenshots… ain't nobody reading all that. I had to resize the browser just to show the two messages I am describing. The notice about old revisions is not the only problem here. As long as there is just so much useless text, people will not read it, and will miss the important messages, even if – especially if! – we make them even bigger.)

Ugh, yes, but everyone's got their favorite bit and will fight to keep it. I'm not sure how expanding to the full width of the content area (as with the classic wikitext editor) would make matters worse. At least it fits in a standard-size laptop screen with minimal scrolling. But yeah, no mobile user is going to read all that.

Change 923695 merged by jenkins-bot:

[mediawiki/core@master] Move "editingold" notice to the top, always add warning frame

https://gerrit.wikimedia.org/r/923695