Move Grid event handlers to a list, add method to add custom handlers (…

…#76)

* Move Grid event handlers to a list, add method to add custom handlers

Change-Id: I2fe67ae961bfb0f7c44ba704346762a0faf6da2c

* Merge branch '7.7' into grid-event-refactoring

client/src/main/java/com/vaadin/client/widget/grid/GridEventHandler.java

@@ -0,0 +1,34 @@
+/*
+ * Copyright 2000-2014 Vaadin Ltd.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not
+ * use this file except in compliance with the License. You may obtain a copy of
+ * the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations under
+ * the License.
+ */
+package com.vaadin.client.widget.grid;
+
+import com.vaadin.client.widgets.Grid.GridEvent;
+
+/**
+ * A handler for events emitted by elements in Grid.
+ *
+ * @param <T>
+ *            the grid row type
+ */
+public interface GridEventHandler<T> {
+    /**
+     * Attempts to handle the given grid event.
+     *
+     * @param event
+     *            the event that occurred
+     */
+    public void onEvent(GridEvent<T> event);
+}