Common drop down box select monotonous look good. Sometimes the customer's needs are always very special to write. Colorado but also the support of the election, but also to support the removal of the option selected wrong.
select2 just can quickly achieve this effect.
The first step: introducing select2 related css, js resource file
<ignore_js_op>
Step Two: Documents prepared in accordance with select2 static template
<ignore_js_op> 
The third step: initialize our select2
<ignore_js_op> 
renderings as follows:
<ignore_js_op>
More technical information may concern: gzitcast