If you try to add a patient birthdate from the main find/create patient screen (and also other places in the UI, for example when running a Reporting Framework report), and you click the month, select it (Jan in my example), and then click to select year, the menu with the list of years appears only for a split second. If you click the year again, the menu appears and works properly.
This problem can be exhibited in Google Chrome Version 33.0.1750.154 m, and Internet Explorer 10.0.9200.16844CO.
It works properly in Firefox 26 and Firefox 27.0.1.
This happens with OpenMRS Version: 1.9.7 Build 60bd9b and Version: 1.11.0 SNAPSHOT Build dfa396.