Hide custom button when starting inline edit/add

I added a button beside the delete button. If I click on inline edit I want to hide/disable this button.
I tried in several events of the edit page :

$pageObject->hideItem("filter_button");
events: before display , before process
but the button is still shown <img src='https://asprunner.com/forums/file.php?topicimage=1&fieldname=question&id=27406&image=1&table=forumtopics' class='bbc_emoticon' alt=':(' />