mw.notify notifications are considered sort of "global" notifications for tools and extensions - and they should appear on top of everything else.
Many tools and extensions (MobileFrontend is a noticeable example) use components (like overlays) outside the content div, which means that they appear on top of the mw.notify div and hide it. Moving the notification div to the top seems like a good idea.
Quoting @Krinkle 's concerns (and discussion) from the task:
I'm for moving it to the body. However two things to consider:
- The positioning of the notification container is intentionally relative to the content area so that it doesn't overlap with personal tools and search (Vector/MonoBook skin). It only moves to an absolute position if the user is scrolled down. Be sure to verify this still works as intended.
- I'm not convinced that it is intentional to have notifications go over top of modal dialogs. I recall several gadgets that bring things to the attention of the user via non-autohide notification bubbles which then have a clickable button in it that opens a modal. I suppose we can still make this change with the expectation that such an application will programmatically hide the notification once the button is clicked - for the benefit of other (autohide) notifications being visible (instead of being trapped behind the modal and expiring before the user sees them).
This second point is probably worth a release note and notice to developers. Maybe create a task and tag it with Notice and Developer-notice, and make sure it gets into Tech News for on-wiki and the Wikitech-ambassadors mailing list.