1)I think that Ideone should not make it’s code public
2)There should be a cumpolsory option of username and password for ideone which should be logged in with the username and then only ideone can be opened so that the codes are never public.
3)Before every problem statement the first line should be written that if you are using ideone then make it private , a link should be provided so that they can open ideone page and make their codes private
4)codechef should request ideone to make automatically the codes private
5)sometimes deserving persons are not selected because someone else copies code from ideone and gets selected in may contests like acm-icpc , snackdown ,etc.