You can hook it up with add_action(‘admin_bar_menu’, to remove or change what you need.
For example, if you want to remove the annoying wordpress logo (imagine facebook having the PHP.net logo on their header) You can use: remove_menu(‘wp-logo’);
Here is a larger article i found via a google search that might help.
http://sumtips.com/2011/03/customize-wordpress-admin-bar.html
I have seen this link. its helpful. thanks. but I want the specifics of how bp links are hooked to adminbar. which file is this done in?
thanks again @mercime. this is not what i was looking for but it is helpful. I was actually searching for the submenu items added to groups or forums in the drop down. Found it in the loader files.
thanks.