How to use mixing Focusable so that cell edit mode turn off when click outside panel?

I have a Fiddle ready to demonstrate the issue: http://ift.tt/1tSby3X

In a grid with cellediting, if I'm editing a text or number using textfield, so in 'edit' mode and I click on the background of an outside panel, so in this example on the south panel, the edit cell will turn off, and we can see that visually.

In the same grid I have a widgetcolumn that is using img. Img has the mixing Focusable and so I expect it handle this by default, but it doesn't.

So you can reproduce with:

- Open west panel

- Click on column 'critical'

- You will see the yellow background on the cell, this show you it's in edit mode

- However, if you click on another cell of the grid, the edit mode will be cancelled on that 'critical' cell

How to use mixing Focusable so that cell edit mode turn off when click outside panel?