Magento display category dropdown in admin configuration

Hi Friends

I am creating a simple script for display category in configuration here is my code

My system.xml code
Path : app/code/local/My/Module/etc

<?xml version="1.0" encoding="UTF-8"?>
<config>
    <tabs>
        <my translate="label" module="lastminute">
            <label>My Extensions</label>
            <sort_order>100</sort_order>
        </my>
    </tabs>
    <sections>
        <my translate="label" module="lastminute">
            <label>My Module Options</label>
            <tab>my</tab>
            <sort_order>1000</sort_order>
            <show_in_default>1</show_in_default>
            <show_in_website>1</show_in_website>
            <show_in_store>1</show_in_store>

            <groups>
                <my_group translate="label" module="module">
                    <label>General</label>
                    <frontend_type>text</frontend_type>
                    <sort_order>1000</sort_order>
                    <show_in_default>1</show_in_default>
                    <show_in_website>1</show_in_website>
                    <show_in_store>1</show_in_store>

                    <fields>
                        <module_choose_category translate="label comment">
                            <label>Category: </label>
                            <comment>Choose category.</comment>
                            <frontend_type>multiselect</frontend_type>
                            <source_model>my_module/system_config_source_category</source_model>
                            <sort_order>2</sort_order>
                            <show_in_default>1</show_in_default>
                            <show_in_website>0</show_in_website>
                            <show_in_store>0</show_in_store>
                        </module_choose_category>
                        <module_choose_assing_category translate="label comment">
                            <label>Categroy to assing this products: </label>
                            <comment>Select categroy.</comment>
                            <frontend_type>select</frontend_type>
                            <source_model>my_module/system_config_source_category</source_model>
                            <sort_order>4</sort_order>
                            <show_in_default>1</show_in_default>
                            <show_in_website>0</show_in_website>
                            <show_in_store>0</show_in_store>
                        </module_choose_assing_category>
                    </fields>
                </my_group>
            </groups>
        </my>
    </sections>
</config>

And now create Category.php
Path: app/code/local/My/Module/Model/System/Config/Source
And add this code

<?php
class My_Module_Model_System_Config_Source_Category extends Mage_Adminhtml_Model_System_Config_Source_Category
{
    public function toOptionArray($addEmpty = true)
    {
        $collection = Mage::getModel('catalog/category')->getCollection()->addAttributeToSelect('*');

        $options = array();      
        /*if ($addEmpty) {
            $options[] = array(
                'label' => Mage::helper('adminhtml')->__('-- Please Select a Category --'),
                'value' => ''
            );
        }*/
      
        foreach($collection as $category){
            if($category->getName() != 'Root Catalog'){
                $options[] = array(
                   'label' => $category->getName(),
                   'value' => $category->getId()
                );
            }
        }
        return $options;
    }
}

And logout admin panel re-login and clear cache and go to configuration your tab -> configuration tab you can see category multiselect dropdown and single dropdown

hope it's helpful of you ;)