When adding a new bug in bmo4.0, the "Possible duplicates" field tells me about related bugs - pretty nice. I'd like to be added to CC fields of some of those bugs, so I click 'Add me to the CC list'. Unfortunately, that button takes me to the new page. That would only be the right behaviour if that bug was a duplicate of the one I'm filing, but it's not, it's just an interesting related bug. The optimal solution is that "Add me to the CC list" is an ajaxy button, which is what I expect in this day and age. If it must take me to the other page, then can you make it appear as a normal link so that I can middle-click it at least?
I agree that this is confusing.