torbutton blocks image titles even when tor mode is off.
Canonical test case is https://xkcd.com - each comic has a < img src="url" title="some text here" > which displays when the cursor hovers over the image. Or at least, it does if I go into about:addons and disable torbutton. If I enable the extension, the title= doesn't appear, even if we're in "tor mode disabled".
Trac:
Username: valdis