TableClickForwarder add-on

Flow
2

It works fine. Currently i try to do is: Is the element a button, the event should not pass.
So i tried onMouseUp

if (el == null ||el instanceof ButtonElement)
    {          return;    }

The element is always [object HTMLTableCellElement]
, altough i pressed a label or button

EDIT: More Infos:

I have a table cell with a HorizontalLayout. The HorizontalLayout contains a Label and a Button. How can i different a click on the button or label with the element el? If the button is clicked, i don’t want pass the event (don’t select the row)