I don't know whether this is an issue with FireBug (1.12.8) or with Tab Mix Plus (0.4.1.3.1) running on FF29.01.
When I was running FF28, duplicating a tab using Ctrl-Alt-T was working correctly.
Now
using FF29, if I press Ctrl-Alt-T with FireBug activated, it causes a
new tab to appear, but the page is not loaded... it is simply blank
(there is also no source).
With FireBug deactivated, Ctrl-Alt-T works as expected.
Not a biggie, but I do use "duplicate tab" regularly, so annoying to have to work around.
Have also posted on the forum for Tab Mix Plus...
http://tmp.garyr.net/forum/viewtopic.php?f=2&t=18710Cheers,
Tom