that didn't really help. for i am looking for "menu_object" and cannot locate it. try this:
navigate through 'apps' > 'panel' > 'objects'
once there, find the object that is type "menu_object" (you can see this on the right)
check "use_custom_icon" and then double click on "custom_icon". Enter the path to one of the start buttons and it should change instantly.