Normally, without even looking, I'd say that would happen when someone posted a long URL.
But that's not what's happening. In fact, I can't figure out the pattern at all. The "How to get main text "before" other body html?" thread displays wide enough that I need to scroll horizontally on 600x800... The "Need proof of html 3.x being better for SE's" thread doesn't force me to scroll.
>>On the "How to get main text before" thread, I don't get a horizontal scroll at 800x600.<<
Interesting... I tried putting my browser completely full screen, and I still get scrolling.
I'm going to try something here. Thus far this thread has not gone wide. I've just started a thread in the eCommerce forum that is wide... only two posts on it... no URLs at all. It's the one about optimizing a Soft Cart site. I'm going to insert the link here [webmasterworld.com], but not display the URL, to see if that has any effect on this thread.
NS 4.77 here and I don't see it in the "How to get main text before" thread but I have seen it in other threads recently, can't recall where now... Also, a Google (I think!) thread is rendering with excessive width in the LEFT column (User Profile et al) and a narrowed right column, text area, but no scrolling required. It appears to be related to an extended title (containing a URL?)
I gotta start making notes... And I'll bring this to Brett's attention.
I agree with DaveAtIFG. I have seen where the left column goes wide and the right text column becomes elongated. The "How to get main text before" thread does not require scrolling - using a 19" monitor @ 800 x 600