title: Magento : System/Config Add Custom Value in MultiSelect
body: <p>i have created one simple Module. i have created system.xml. there is one field <strong>Multiselect</strong> i want to add custom Value in multiselect field.</p>
  
  <p>is it possible to add custom Value in multiselect field ?</p>
  
  <pre><code> &lt;Data translate="label"&gt;
   &lt;label&gt;Select Socail Media&lt;/label&gt;
   &lt;comment&gt;Select Social Media To fdisplay ion Front Side&lt;/comment&gt;
   &lt;front_end_type&gt;multiselect&lt;/front_end_type&gt;
   &lt;source_model&gt;adminhtml/system_config_source_country&lt;/source_model&gt;
   &lt;sort_order&gt;3&lt;/sort_order&gt;
   &lt;show_in_default&gt;1&lt;/show_in_default&gt;
   &lt;show_in_website&gt;1&lt;/show_in_website&gt;
   &lt;show_in_store&gt;1&lt;/show_in_store&gt;
   &lt;/Data&gt;    
  </code></pre>
  
  <p>in Multiselect Options i want to add my Custom Option like: Data1, Data2 , Data3 etc..</p>
  
  <p>how can i do that? is it possible?</p>