This is a regression for bug 17773, the UI refresh.
I have a fix for this.
Created attachment 21412 [details] Proposed patch
Created attachment 21421 [details] Screenshot Large Rows
Created attachment 21422 [details] Screenshot Small Rows
Created attachment 21434 [details] Proposed patch v2
Comment on attachment 21434 [details] Proposed patch v2 r=me
Tim, are you planning to land this fix?
I landed this a while ago, just forgot to update the bug. r34272