[IMP] mail: client action: focus on composer when opening a channel

Disable this feature on mobile as we don't want the mobile composer to open
each time we switch from an channel to an other.

addons/mail/static/src/js/client_action.js

@@ -5,6 +5,7 @@ var chat_manager = require('mail.chat_manager');
 var ChatComposer = require('mail.ChatComposer');
 var ChatThread = require('mail.ChatThread');
 
+var config = require('web.config');
 var ControlPanelMixin = require('web.ControlPanelMixin');
 var core = require('web.core');
 var data = require('web.data');
@@ -314,6 +315,9 @@ var ChatAction = Widget.extend(ControlPanelMixin, {
 
         return this.fetch_and_render_thread().then(function () {
             self.thread.scroll_to({offset: new_channel_scrolltop});
+            if (!config.device.touch) {
+                self.composer.focus();
+            }
             self.action_manager.do_push_state({
                 action: self.action.id,
                 active_id: self.channel_id,

addons/mail/static/src/js/composer.js

@@ -479,6 +479,9 @@ var Composer = Widget.extend({
     is_empty: function () {
         return !this.$input.val().trim() && !this.$('.o_attachments').children().length;
     },
+    focus: function () {
+        this.$input.focus();
+    },
 });
 
 return Composer;