Implemented "cancel" for edit

src/components/DropdownMenu/DropdownMenu.scss

@@ -21,22 +21,30 @@
     z-index: 1000;
     border: 1px solid #eee;
     min-width: 150px;
-    padding: 5px 0;
   }
 }
 
 .menuItem {
   margin: 0;
   padding: 5px 10px;
-  height: 24px;
+  height: 32px;
 
   display: flex;
   justify-content: space-between;
   align-items: center;
   cursor: pointer;
+  border-left: 2px solid transparent;
+
+  span {
+    margin-top: 2px;
+  }
 
   a {
     color: $textColor;
     text-decoration: none;
   }
+
+  &:hover {
+    border-left: 2px solid #2196F3;
+  }
 }

src/scenes/DocumentEdit/DocumentEdit.js

@@ -1,5 +1,6 @@
 import React, { Component } from 'react';
 import { observer } from 'mobx-react';
+import { browserHistory } from 'react-router';
 
 import store from './DocumentEditStore';
 
@@ -50,6 +51,10 @@ class DocumentEdit extends Component {
     }
   }
 
+  onCancel = () => {
+    browserHistory.goBack();
+  }
+
   state = {
     scrollTop: 0,
   }
@@ -85,6 +90,9 @@ class DocumentEdit extends Component {
           <MenuItem onClick={ this.onPreviewToggle }>
             Preview <Switch checked={ store.preview } />
           </MenuItem>
+          <MenuItem onClick={ this.onCancel }>
+            Cancel
+          </MenuItem>
         </DropdownMenu>
       </Flex>
     );

src/scenes/DocumentEdit/DocumentEditStore.js

@@ -1,7 +1,7 @@
 import { observable, action, computed, autorun } from 'mobx';
 import { client } from 'utils/ApiClient';
 import localforage from 'localforage';
-import { browserHistory } from 'react-router'
+import { browserHistory } from 'react-router';
 
 const DOCUMENT_EDIT_SETTINGS = 'DOCUMENT_EDIT_SETTINGS';