function isDescendant(parent, child) {

     var node = child.parentNode;

     while (node != null) {

         if (node == parent) {

             return true;

         }

         node = node.parentNode;

     }

     return false;

}

​

document.getElementById('toolbar').addEventListener('blur',function(e){

    if ( e.relatedTarget && !isDescendant(this, e.relatedTarget)) {

        console.log('real blur');

    }

    else {

        console.log(e);

        console.log('sibling, or unknown');

    }

}, true);