When I visit Template:Tropestub while logged in, I get anon's view (Create account | Log in) and then my own logged-in sidebar (Damian Yerrick (0) | Talk | Sandbox | Preferences etc.) slides in to replace it. When I click "View source" on anon's view, I get taken to an edit form, but when I try to preview or submit from this edit form, it takes me back to anon's view where my logged-in sidebar once again slides in.
Template talk:Tropestub
I don't know why I didn't see this message before now, but you were having your problem in the middle of Orain doing a mess of things that made a mess of things. See how it works now.
All appears to be solved now.
Good. I had thought it might, as I was unable to replicate your problem this morning. But things are sometimes subtly different for me as an admin from what they are for a regular user, so I couldn't be 100% sure.
If you want to see how the other half live, you can have your browser open a new window in "porn mode" (incognito, private, etc.) to view attwiki* as an IP visitor sees it.
* You're not dealing with AT&T.
Good point; I hadn't even considered that.
Also, given how many times I've accidentally done that through a context menu link instead of just "open in a new tab/window" (far more often than I've ever done it deliberately) I wonder if maybe the same kind of thing contributed to your original symptoms?
I usually middle-click (when using a mouse) or Ctrl+click (when using a laptop trackpad that lacks a middle button) to open a page in a new tab. I see accidental porn mode activation happen more often on my tablet, which doesn't have a dedicated button to open a page in a new tab but instead uses a long-press to reveal a context menu.