Add WordPress Internal Link Popup

gistfile1.txt

/*
 * Load the scripts needed so we can display the Internal Link Popup
 */
add_action( 'admin_enqueue_scripts', 'loadScripts', 800 );
function loadScripts( $hook ) {
	if( is_admin()) {
		wp_enqueue_script( 'wplink' );
		wp_enqueue_style( 'editor-buttons' );
	}
}

/*
 * Include the javascript and PHP file needed to display the Internal Link Popup
 */
add_action( 'admin_footer', 'adminFooterScripts' );
function adminFooterScripts() {
	if( is_admin())
	{
		// Require the core editor class so we can call wp_link_dialog function to print the HTML.
		// Luckily it is public static method, so no need to have a hidden wp-editor
		require_once( trailingslashit( ABSPATH ) . "wp-includes/class-wp-editor.php" );
		_WP_Editors::wp_link_dialog(); ?>
		<script type="text/javascript">
			/* We need ajaxurl to send ajax to retrive links. This script can also be localized */
			var ajaxurl = "<?php echo admin_url( 'admin-ajax.php'); ?>";
			jQuery(function ($){
				/* THE_ID_OF_THE_ELEMENT_CLICKED => usually a text area or input text */
				$('#THE_ID_OF_THE_ELEMENT_CLICKED').click(function (){
					wpLink.open('THE_ID_OF_THE_ELEMENT_CLICKED'); /* Bind to open the link editor */
				});
			})
		</script><?php
	}
}