- Visit Special:Preferences > Appearance
- Under "Advanced options" there's a preference labeled "Threshold for stub link formatting (bytes):"
- Click the reddish "stub link" link.
Result: you go back to the main Preferences page.
Expected result: I expected a link to a missing page (because reddish) that's intended to more information about "stub links".
But this behavior is actually intended, see brion's comment in T11886: Provide a means to give an example "stub" link in "stubthreshold" message. The 'stub-threshold' message is the HTML:
Threshold for <a href="#" class="stub">stub link</a> formatting (bytes):
If you look carefully at Preferences, you're not seeing a redlink to a missing explanation of what a "stub link" is, you're seeing the actual presentation of a stub link via a link styled with class="stub".
The fix is for the message to be clearer, e.g.:
"Threshold in bytes for stub link rendering (sample):"
While I'm here, the qqq.json doc for 'stub-threshold' gives the wrong tab and is unhelpful (ditto 'imagemaxsize'):
Used in [[Special:Preferences]], tab "Misc".
Note the entire feature is controversial, T30426: Remove stub link formatting user preference from MediaWiki core.