Merge pull request #586 from tsuiyuenhong/bugfix/fix_create_button_hittest_bug

bugfix: click on the edge of the `add_button` that create the document does not respond to event

frontend/app_flowy/lib/workspace/presentation/home/menu/app/header/add_button.dart

@@ -83,6 +83,7 @@ class CreateItem extends StatelessWidget {
     return FlowyHover(
       style: config,
       child: GestureDetector(
+        behavior: HitTestBehavior.opaque,
         onTap: () => onSelected(pluginBuilder),
         child: FlowyText.medium(
           pluginBuilder.menuName,