Remove optgroup from selectbox

HTML optgroup element creates a grouping of options within a select  element in web page. You might be working on optgroup in select box. Here is the simple script for the addition and deletion of optgroups. 

Prevent Grey box from hiding drop down

Today I was working with Grey box component and every thing was going smooth... But suddenly I came to know that select box on parent page become invisible as the Grey box popup comes up.