Dynamic Action on Button-Item

Reading the post How to Trigger Dynamic Action From Button by Martin Giffy D'Souza, I decided to give the dynamic action on buttons another try.
The action on the 'normal' button (in a region position) can be added as described and works perfectly, but if I want to do the same with the button-item, I get an unwanted effect - despite of disabling/rewriting the click event, the site will redirect: the apex.submit does the job.
The only trick that works is to remove the attribute 'onclick' explicitly attr('onclick','') and then to add the new event.

Create Dynamic Action -> Advanced -> Event: Page Load -> Action: Excecute JS Code

$(this.affectedElements) //when you choose Selection Type: Item(s) (by HTML button)
or
$('#custom') //with known id
  .attr('onclick','')
  .click(function(){alert('my event')})


This can, of course, be splitted into OnLoad action (disable the click first) and then another one to add a custom event.
All roads lead to Rome.