stores a collection of buttons resided in the pop-up task's details form
gantt.config.quickinfo_buttons=["icon_delete","icon_edit","advanced_details_button"];
gantt.locale.labels["advanced_details_button"] = "Advanced Info";
gantt.init("gantt_here");
gantt.$click.buttons.advanced_details_button=function(id){
gantt.message("These are advanced details");
return false; //blocks the default behavior
};
This option is defined in the Quick Info extension, so you need to activate the quick_info plugin.