Add button to open new conversations

lib/ui/routes/main_route/tablet_route.dart

@@ -1,4 +1,5 @@
 import 'package:comunic/ui/routes/main_route/main_route.dart';
+import 'package:comunic/ui/widgets/tablet_mode/conversations_area_widget.dart';
 import 'package:comunic/ui/widgets/tablet_mode/current_user_panel.dart';
 import 'package:comunic/ui/widgets/tablet_mode/global_search_field.dart';
 import 'package:comunic/ui/widgets/tablet_mode/memberships_panel.dart';
@@ -25,8 +26,11 @@ class _TabletRouteState extends State<TabletRoute> {
 
   Widget _buildAppBar() => ComunicTabletAppBarWidget();
 
-  Widget _buildBody() => Row(
+  Widget _buildBody() => Stack(
-        children: <Widget>[_buildLeftPane(), _buildRightPane()],
+        children: [
+          Row(children: <Widget>[_buildLeftPane(), _buildRightPane()]),
+          Positioned(right: 0, bottom: 0, child: ConversationsAreaWidget())
+        ],
       );
 
   Widget _buildLeftPane() => Theme(

lib/ui/widgets/tablet_mode/conversations_area_widget.dart

@@ -0,0 +1,31 @@
+import 'package:flutter/material.dart';
+
+/// Conversations area widget
+///
+/// This widget allow floating conversations in tablet mode
+///
+/// @author Pierre
+
+class ConversationsAreaWidget extends StatefulWidget {
+  @override
+  _ConversationsAreaWidgetState createState() =>
+      _ConversationsAreaWidgetState();
+}
+
+class _ConversationsAreaWidgetState extends State<ConversationsAreaWidget> {
+  @override
+  Widget build(BuildContext context) {
+    return Row(
+      children: <Widget>[_buildOpenButton()],
+    );
+  }
+
+  /// Add a button to open new conversations
+  Widget _buildOpenButton() => Padding(
+        padding: const EdgeInsets.all(15.0),
+        child: FloatingActionButton(
+          onPressed: () {},
+          child: Icon(Icons.message),
+        ),
+      );
+}