I can console the data of chat manager from mail as below.

var chat_manager = require('mail.chat_manager');
console.log("chat_manager", chat_manager);

but, showing "undefined" when I try to console 'mail.systray'.

I don't know why it is. ! :(
(I think that js has no any return)

I too having the same problem for inheriting the below js files.

1. window_manager.js file in mail module

var window_manager = require('mail.window_manager');

2. client_action.js file in mail module

var chat_client_action = require('mail.chat_client_action');

im always receiving undefined value for above code.

Any solution to fix the issue?

Note:

i'm also extending some other files in mail module that are working,

chat_manager.js & systray.js files.