How to hide button is Sencha Touch 2.1 - sencha-touch

Question

I've found similar questions on this site but none of the answers has been working for me. This is button I want to hide (view):
{
xtype: 'button',
id: 'btn_messenger',
text: 'Messenger'
}
Controller for that view has init function:
init : function() {
var me = this;
me.callParent();
me.hideMessengerButton(me);
}
This is the function that should hide button:
hideMessengerButton: function(me) {
var user = me.getLoggedUser(); // return user or undefined
if (user == undefined) {
Ext.select('#btn_messenger').hide(); // Does nothing
}
}
I've tried these options:
Ext.getCmp('btn_messenger').hide(); // Ext.getCmp('btn_messenger') returns undefined
Ext.getCmp('#btn_messenger').hide(); // Ext.getCmp('#btn_messenger') returns undefined
In controller's refs there is btn_messenger: '#btn_messenger', so I've tried:
this.getBtn_messenger().hide() // this.getBtn_messenger() returns undefined
Thanks for help in advance.
PS.: I don't know if this matters but the view mentioned above is not the main view. It is pushed after button tap on the main view.
EDIT:
Here is the controller:
Ext.define('First.controller.HomePage', {
extend : 'First.controller.Controller',
requires : ['First.view.Main', 'First.view.HomePage'],
config : {
refs : {
pnl_home: 'pnl_home',
btn_messenger : '#btn_messenger'
},
control : {
btn_messenger : {
tap : 'btn_openMessenger'
}
pnl_home: {
show: 'hideMessengerButton'
}
},
},
init : function() {
var me = this;
me.callParent();
},
btn_openMessenger : function() {
Ext.Msg.alert('Open', 'Messenger');
},
/**
* Hide meseenger button when user's not logged in
*/
hideMessengerButton : function() {
var me = this;
var user = me.getLoggedUser();
if (user == undefined) {
me.getBtn_messenger().setHidden(true);
}
}
});

Answer 1

http://docs.sencha.com/touch/2-1/#!/api/Ext.Button-method-setHidden
in your action
replaces refs
refs : {
btnMessenger: '#btn_messenger'
},
then when you need this button on action use next
this.getBtnMessenger().setHidden(true)
also on init button are not yet added to dom as i remember
lauch : function() {
this.hideMessengerButton();
},
hideMessengerButton: function() {
var user = this.getLoggedUser(); // return user or undefined
if (user == undefined) {
this.getBtnMessenger().setHidden(true); // Does nothing
}
}

Answer 2

I've added pnl_home: 'pnl_home', to refs and called show event on the panel. Modified code can be found above, in my initial post.