handling lost focus in case of fade

fixes: #1017

Author: laveesingh

src/mixins/helpers.js

@@ -178,6 +178,10 @@ var helpers = {
           this.props.afterChange(animationTargetSlide);
         }
         delete this.animationEndCallback;
+        if (this.props.fade) {
+          const focusableSlide = ReactDOM.findDOMNode(this.track).children[animationTargetSlide]
+          focusableSlide.focus()
+        }
       };
 
       this.setState({