Dojo bug: Uncaught TypeError: Cannot read property 'className' of null

[GibboK]

Dojo bug: Uncaught TypeError?: Cannot read property 'className' of null

To reproduce this issue follow the steps on this page:

​https://jsbin.com/ciroyas/edit?html,console,output

1. Click on dijit/form/Select on the left side, dijit/popup will popup with a list of values.
2. Keep dijit/popup open with the list of values.
3. Double click on an item inside 'dojo/dnd/Source' on right side.
4. An error in console appears:

Uncaught TypeError: Cannot read property 'className' of null

Basically, it is not possible to correctly destroying dijit/form/Select when its dijit/popup is open, if User double click on an 'dojo/dnd/Source' item.

Observations: I have noticed that the event focusin is not being fired on body when user mouse click an item in a dojo/dnd/Source.

This is oberservable at: Line 118 from dojo repo focus.js ​https://github.com/dojo/dijit/blob/master/focus.js

When instead on other dojo widgets, for example dijit/form/Button, the focusin event is being fired properly.

If focusin is not detected properly, function _onBlur in file _HasDropDown is not being called causing this error.

I kindly ask you if you could verify this issue and meanwhile provide a workaround if available.

Thanks for your support.

[GibboK]

Minimal example