I have the Recent Comments widget running in the left sidebar on the newspaper site. If somebody posts a URL in their comment in the first few lines, it would bleed over into the center column. I posted about this in the support forum at wordpress.org, and some kind soul told me to use the following, which I pasted into the ATO/Add HTML& CSS inserts/CSS inserts:

ul#bfarecentcomments {
overflow: hidden;
}

Worked like a charm.

Good to know, thanks for sharing!