I noticed the modifications made to the forum to make it expand as you increase the size of the window are actually broken when posting a new topic, replying to an existing one, or editing a post. That is, the /post page specifically. If you expand the window, the page expands infinitely and will not contract when you shrink the window.
Additionally, it will expand the page horizontally even if you're only expanding (or SHRINKING!) the window vertically (i.e. when you put your cursor on the bottom edge of the window and drag either down or up). This scenario is how I realized the infinite expansion issue exists as it makes it REALLY obvious.
Not really a huge issue, but it's there.
Sorry Tales peeps, even when not working, QA TESTERS GOTTA TEST!
EDIT: This actually happens on ALL pages that have the text editor for posts - for example on the bottom of a thread if you drag the bottom of the browser window up and down the text editor will keep expanding until it reaches the borders of the page, which will then start expanding the page itself. You can even try it on this very page to see it yourself.