prompt the user if they try leaving the page before confirming their tip
prompt the user if they try leaving the page before confirming their tip

eXcomm/gratipay.com,gratipay/gratipay.com,gratipay/gratipay.com,mccolgst/www.gittip.com,mccolgst/www.gittip.com,studio666/gratipay.com,mccolgst/www.gittip.com,studio666/gratipay.com,eXcomm/gratipay.com,eXcomm/gratipay.com,mccolgst/www.gittip.com,gratipay/gratipay.com,studio666/gratipay.com,eXcomm/gratipay.com,studio666/gratipay.com,gratipay/gratipay.com