This is a convenience function for launching the default application to show the uri. The uri must be of a form understood by GIO (i.e. you need to install gvfs to get support for uri schemes such as http:// or ftp://, as only local files are handled by GIO itself). Typical examples are - file:///home/gnome/pict.jpg - http://www.gnome.org - mailto:megnome.org
Ideally the timestamp is taken from the event triggering the gtk_show_uri() call. If timestamp is not known you can take GDK_CURRENT_TIME.
This is the recommended call to be used as it passes information necessary for sandbox helpers to parent their dialogs properly.