Last modified: 2011-08-04 18:56:07 UTC
When embedding an image like this <code>[[File:Placeholder.png|link=|Caption]]</code>, the "caption" which should pop up as a tooltip doesn't show and I've found that it is because the link attribute is blanked (this is done intentionally as per [[:en:WP:ICON]] and [[:en:WP:ALT]] guidelines).
This sounds like a duplicate of bug 16912. Where are you seeing this broken behavior? On the English Wikipedia? On your own wiki? Somewhere else?
It looks like r50641 covered two cases (cf. <r1=50640&r2=50641">http://svn.wikimedia.org/viewvc/mediawiki/trunk/phase3/maintenance/parserTests.txt?pathrev=50641&r1=50640&r2=50641>). I don't think anyone ever thought to test with a blank |link= (it's a bit of a hack). This seems like a valid bug.
The title attribute should be added to the <img> Actual: <img alt="Caption" src="//upload.wikimedia.org/wikipedia/commons/4/47/Placeholder.png" width="678" height="841" /> Expected: <img alt="Caption" title="Caption" src="//upload.wikimedia.org/wikipedia/commons/4/47/Placeholder.png" width="678" height="841" />
Blanking the link attribute is an increasingly common practice in English Wikipedia. The guideline suggests that small icon image which is used inline should not be clickable, otherwise it may distract the reader and it is usually not worth checking if higher resolution avaiable of the icon. Someone tested that the absent of tooltip can be substituted by title attribute of the div tags that nest the File syntax. See my en.wp sandbox [[User:Sameboat/sandbox2]].
*** This bug has been marked as a duplicate of bug 21454 ***
