The point of this thread is more to act as an advance warning/heads up, explaining problems people may be having with their theme - given that Firefox 4 and IE 9 (both of which are affected) will be released in ~2 weeks - and so might result in an influx of support threads here.
I've checked the latest version of default using the preview here:
http://wp-themes.com/default/?TB_iframe=true&width=1585&height=900
...and it seems to have had the issue fixed.
So presumably as long as people are using default and keeping it up to date, then they won't be affected.
However, for the many sites that use a custom theme based on Default/Kubrick, who haven't incorporated newer Kubrick/Default changes, then they may be affected.
eg like this user's custom theme based on Kubrick:
http://www.buzzmachine.com/
tl;dr...
- Fault is only in older versions of the theme
- So agree it's the responsibility of the blog owner to update/change to a non-broken theme
- This thread is just attempting to give advance warning to those who offer support/triage, given that Firefox 4/IE 9 are going to be released in <2 weeks
Sticky/known issues list perhaps?