Dropdownlist with Add and Remove function

Dear Yii Users,

I am using the code below display multiple selected values for users to choose from.

	<div class="row">

		<?php echo $form->labelEx($model,'site_staff'); ?>

		<?php //echo $form->textField($model,'site_staff',array('size'=>60,'maxlength'=>255)); ?>

		<?php //echo $form->dropDownList($model,'site_staff', CHtml::listData(Biodata::model()->findAll(), 'full_name', 'full_name'), array('empty'=>'Select')); ?>

		<?php echo $form->dropDownList($model,'site_staff',CHtml::listData(Biodata::model()->findAll(),'full_name','full_name'),array('multiple'=>'true','prompt'=>'select ','selected'=>'selected'));?>

		<?php echo $form->error($model,'site_staff'); ?>


I am trying to achieve the following but have no idea how to go about:

  1. Add and remove function

    • When a user choose one or more, by clicking "Add", will display the selected value in another dropdown list

    • User can also remove any selected data in the latter dropdown list

So far, the single dropdown works well but users need to use CTRL-CLICK to select more than one option which is not a feasible way of selecting.

Any help is greatly appreciated. :D