Have you also by chance applied the threading patches from Chris January (
RoundCube Mailing Lists)? Because I believe the problem is related to the threading. I think the problem lies near line 913 (may be diff. on your install because of some of the patches I have) of ./roundcubemail/program/js/list.js where this conditional fails because of the threading patches:
if (((node = obj.childNodes[i].firstChild) &&
(node.nodeType==3 || node.nodeName=='A')) &&
(this.subject_col < 0 || (this.subject_col >= 0 && this.subject_col == c)))
Where in the threading case the firstChild is div.leaf and is not of nodeType 3 or nodeName A. In the threading case we actually want childNode[2] not firstChild. I'll write up a patch later today to fix this for the threading implementation.
If you think the issue you are having is not the threading, then please let me know a few more details about what the makeup of each row is in the interface. I don't think so, but perhaps some of the threading stuff slipped through in my patches or the theme itself.
Nathan