Add style option to DragBox interaction

src/objectliterals.jsdoc

@@ -318,6 +318,7 @@
  * @property {ol.events.ConditionType|undefined} condition A conditional
  *     modifier (i.e. Shift key) that determines if the interaction is active
  *     or not, default is always.
+ * @property {ol.style.Style} style Style for the box.
  * @todo stability experimental
  */
 

src/ol/interaction/dragboxinteraction.js

@@ -44,11 +44,18 @@ ol.interaction.DragBox = function(opt_options) {
   this.behavior_ = goog.isDef(options.behavior) ?
       options.behavior : goog.nullFunction;
 
+
+  /**
+   * @private
+   * @type {ol.style.Style}
+   */
+  var style = goog.isDef(options.style) ? options.style : null;
+
   /**
    * @type {ol.render.Box}
    * @private
    */
-  this.box_ = new ol.render.Box();
+  this.box_ = new ol.render.Box(style);
 
   /**
    * @private