The best way to see phpMyAdmin in action is to try it on our demo server, where you have full control on MySQL.
Please not change root, debian-sys-maint or pma user password or limit their permissions. If you do so, demo can not be accessed until privileges are restored, so you just break things for you and other users. Feel free to try any of the phpMyAdmin features. If you break something, just wait a while. The database configuration resets every hour. Databases are cleaned weekly, so do not expect that your data will stay there forever.
Login is root with empty password or any user you create.
Please note that git versions don't have to be working, that's why it's development version :-).