Missing CSS property breaks dropdown visually

Last week I upgraded from 6.x-1.6 to 6.x-1.7 on one of our sites. Unfortunately this visually broke the language dropdown, as that the select element was seperated from the dropdown arrow. I compared the 6.x-1.6 and 6.x-1.7 CSS, and then saw that the directive float:left was missing from the CSS class dd_after. Adding that float directive solved the problem.