[xwiki-users] How to add a sub-menu button for image menu in wysiwyg editor inline form

Hi, all, I am trying to add an addComments sub-menu item to image button from the menu bar of WYSIWYG editor, what it does is to add comments for an image inserted in the editor because I need to explain what each image is about after I put it in the editor, I checked the class:XWiki.WysiwygEditorConfigClass and the wysiwyg.js, I added a sub-menu in the WysiwygEditorConfigClass for image menu, but after that, I got lost, this sub-menu button is supposed to connect to a plugin to trigger java to run I believe since it is a plugin and each sub-menu like imageInsertAttached, imageInsertURL is a plugin, but I could not find the code where it calls a plugin, so how is the sub-menu button hooked to the plugin? when a user clicks on the submenu button in the editor (inline form) page, which javascript function gets called? Thanks very much in advance!! Dave