Add some helper methods in Layer and PropertyStack

src/style_manager/model/Layer.js

@@ -33,6 +33,15 @@ module.exports = Backbone.Model.extend({
     }
   },
 
+  /**
+   * Get property at some index
+   * @param  {Number} index
+   * @return {Object}
+   */
+  getPropertyAt(index) {
+    return this.get('properties').at(index);
+  },
+
   getPropertyValue(property) {
     let result = '';
     this.get('properties').each(prop => {

src/style_manager/model/PropertyStack.js

@@ -20,6 +20,14 @@ module.exports = Property.extend({
     Property.callInit(this, props, opts);
   },
 
+  getLayers() {
+    return this.get('layers');
+  },
+
+  getCurrentLayer() {
+    return this.getLayers().filter(layer => layer.get('active'))[0];
+  },
+
   getFullValue() {
     return this.get('detached') ? '' : this.get('layers').getFullValue();
   }