Some layout improvements and fixes

app/src/main/res/layout/fragment_message_list.xml

@@ -1,6 +1,7 @@
 <?xml version="1.0" encoding="utf-8"?>
 <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
                 xmlns:app="http://schemas.android.com/apk/res-auto"
+                xmlns:tools="http://schemas.android.com/tools"
                 android:layout_width="match_parent"
                 android:layout_height="match_parent">
 
@@ -15,7 +16,8 @@
 
         android:paddingBottom="88dp"
         android:scrollbarStyle="outsideOverlay"
-        android:scrollbars="vertical"/>
+        android:scrollbars="vertical"
+        tools:listitem="@layout/message_row"/>
 
     <android.support.design.widget.FloatingActionButton
         android:id="@+id/fab_compose_message"