correct behaviour when using "" as an empty string

Author: h7io

code/DropdownImageField.php

@@ -26,7 +26,7 @@ public function Field($properties = array()) {
 		$source = $this->getSource();
 		$options = array();
 		if($source) {
-			if(is_object($source) && $this->emptyString) {
+			if(is_object($source) && $this->hasEmptyDefault) {
 				$options[] = new ArrayData(array(
 					'Value' => '',
 					'Title' => $this->emptyString,

javascript/ImageSelect.jquery.js

@@ -152,7 +152,7 @@
                     // _chosen: Object {chosen:Chosen}
                     //      Contains the current instance of Chosen class
                     var lis = $(chosen.container).find('.chzn-drop ul li')
-                    var options = $(chosen.form_field).find('optgroup, option');
+                    var options = $(chosen.form_field).find('optgroup, option:not(:empty)');
 
                     for(var i = 0; i < lis.length; i++){
                         var li = lis[i];