Display the list of conversation to open one

lib/ui/widgets/tablet_mode/conversations/conversations_area_widget.dart

@@ -0,0 +1,26 @@
+import 'package:comunic/ui/widgets/tablet_mode/conversations/open_conversation_button_widget.dart';
+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() => OpenConversationButton();
+}

lib/ui/widgets/tablet_mode/conversations/open_conversation_button_widget.dart

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+import 'package:comunic/ui/screens/conversations_list_screen.dart';
+import 'package:flutter/material.dart';
+
+/// This buttons open a menu
+/// to choose a conversation to open
+///
+/// @author Pierre Hubert
+
+class OpenConversationButton extends StatefulWidget {
+  @override
+  _OpenConversationButtonState createState() => _OpenConversationButtonState();
+}
+
+class _OpenConversationButtonState extends State<OpenConversationButton> {
+  bool _showConversationsList = false;
+
+  void _setShowConversationsList(bool s) =>
+      setState(() => _showConversationsList = s);
+
+  @override
+  Widget build(BuildContext context) {
+    return Padding(
+      padding: const EdgeInsets.all(10.0),
+      child: Column(
+        crossAxisAlignment: CrossAxisAlignment.end,
+        children: <Widget>[
+          _showConversationsList ? _buildConversationsList() : Container(),
+          FloatingActionButton(
+            onPressed: () => _setShowConversationsList(!_showConversationsList),
+            child: Icon(_showConversationsList ? Icons.close : Icons.message),
+          )
+        ],
+      ),
+    );
+  }
+
+  Widget _buildConversationsList() => Container(
+      width: 300,
+      height: 500,
+      child: Card(
+        child: ConversationsListScreen(),
+      ));
+}