ckeditor change button icon dynamically

Question

Hi everyone, I am trying to write a plugin for ckeditor, like in the link below http://stackoverflow.com/questions/1139766/ckeditor-custom-plugins-button/1994020#1994020

the problem is, I want the button to change once I click it, and change back, so the users knows something happened. how can i change the path to the icon after the button is added? is there something like editor.ui.editButton?

Thanks!