lookupReference window - strange behaviour ?

First I'd like to say that I haven't used Ext since version 3.4, so I'm kind of new to the changes since, but I try to catchup with the new 5 !

I have created a simple sencha fiddle in order to get the complete scenario: http://ift.tt/YxQbgB

Scenario:

- click topBar button (to create a window only if does not already exists)

- I'm using ViewControllers' lookupReference to search the window, if not find it, create it

- without closing the window, press the button again (should only popup the alert telling that's already there - which is true ... no other code beside lookup is executing)

- close the window

- push the button to create it again

BUMP: lookupReference still returns the component, even if it was destroyed ?

If you close the window each time you create it (not pressing the button if the window exists), it will create it every time.

I don't do anything else in the button handler if it finds it (beside the alert)

What am I doing wrong here ?

lookupReference window - strange behaviour ?