I'm getting a different styling on checkboxes with 2013.3 SP1. Take a look at the attached screenshots, one from version 2013.3.1015 and the other from 2013.3.1114. These are both IE 8, Windows XP Pro. Firefox does not have this difference. In FF, the 1114 version looks the same as the 1015 version Here is a boiled down version of the ASPX page with RadGrid, single column, checkbox in header.