From bug 779686 comment #22:
> If there is a chat window that is right-most, as in this screenshot, does it
> block access to the bottom part of the scrollbars?
> We should move the chat window over just enough to not block any part of the
> scrollbars (even on pages that lack scrollbars, so as not to jump when
> switching tabs or when dynamic changes to content are made).
You're saying scrollbars, but it seems like you're only talking about the vertical scrollbar. How would you address horizontal scrollbar being blocked?
Secondly, I don't think it's kosher to special-case the default scrollbar here and disregard any custom UI implemented by content (such as Facebook's custom scrollbars).
See also bug 779686 comment 57.
Created attachment 655273 [details] [diff] [review]
This patch fixes the vertical scrollbar issue. I don't have a good solution for third-party vertical scrollbars, nested scrollbars, or horizontal scrollbars.
The vertical ones are much more prevalent though, and we should at least fix this first since it's pretty easy.
I spun off the work for horizontal and third-party scrollbars to bug 785591.
Created attachment 655473 [details] [diff] [review]
This patch uses margin instead of padding, which I think is more semantic for the purpose here.
Created attachment 655475 [details] [diff] [review]
Patch for checkin