Add an icon to the conversations windows

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

@@ -74,6 +74,7 @@ class _ConversationWindowState extends SafeState<ConversationWindow> {
     // In case of error
     if (_error)
       return ConversationWindowContainer(
+        icon: Icon(Icons.error),
         title: Text(tr("Error")),
         onClose: widget.onClose,
         onToggleCollapse: _toggleVisibility,
@@ -91,6 +92,7 @@ class _ConversationWindowState extends SafeState<ConversationWindow> {
     // If it is still loading
     if (_conversation == null)
       return ConversationWindowContainer(
+        icon: Icon(Icons.message),
         title: Text(tr("Loading...")),
         onClose: widget.onClose,
         onToggleCollapse: _toggleVisibility,
@@ -99,6 +101,7 @@ class _ConversationWindowState extends SafeState<ConversationWindow> {
       );
 
     return ConversationWindowContainer(
+      icon: Icon(Icons.comment),
       title: Text(_convTitle),
       onClose: widget.onClose,
       onToggleCollapse: _toggleVisibility,

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

@@ -7,6 +7,7 @@ import 'package:flutter/material.dart';
 /// @author Pierre Hubert
 
 class ConversationWindowContainer extends StatelessWidget {
+  final Widget icon;
   final Widget title;
   final void Function() onClose;
   final void Function() onToggleCollapse;
@@ -15,6 +16,7 @@ class ConversationWindowContainer extends StatelessWidget {
 
   const ConversationWindowContainer({
     Key key,
+    this.icon,
     @required this.title,
     @required this.onClose,
     @required this.body,
@@ -35,6 +37,7 @@ class ConversationWindowContainer extends StatelessWidget {
         height: !isCollapsed ? 400 : 40,
         child: Scaffold(
           appBar: AppBar(
+            leading: icon,
             title: GestureDetector(child: title, onTap: onToggleCollapse),
             actions: <Widget>[
               IconButton(icon: Icon(Icons.close), onPressed: onClose),