Fix focus on "+" button in MainActivity

Author: sashaqwert

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

@@ -35,11 +35,13 @@
         android:id="@+id/fab"
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
-        android:layout_alignParentBottom="true"
         android:layout_alignParentEnd="true"
-        android:layout_marginBottom="24dp"
+        android:layout_alignParentBottom="true"
         android:layout_marginEnd="21dp"
+        android:layout_marginBottom="24dp"
         android:clickable="true"
+        android:focusable="true"
+        android:nextFocusLeft="@id/listView_main"
         app:backgroundTint="@color/colorPrimary"
         app:fabSize="mini"
         app:srcCompat="@android:drawable/ic_input_add" />