If you have tooltips disabled in Preferences, the ABBR and ACRONYM tags are still rendered with a dotted line underneath, and the cursor changes to an arrow-with-question-mark when hovered over the text, but nothing else happens. The only way for the user to see the acronym's expansion is to right-click and select Properties, which is not obvious. Suggested fixes: 1) Display tooltips for ABBR and ACRONYM irrespective of the preference. 2) If tooltips are disabled, display the title of an ABBR or ACRONYM in the status bar instead of a tooltip. 3) Allow the user to choose between 1 and 2 with a separate preference.
See also bug 64232, "Separate pref for chrome tooltips". If that bug is fixed by changing the pref to only affect chrome tooltips (and not adding a pref for content tooltips), this bug won't have to be fixed.
*** This bug has been marked as a duplicate of 64232 ***