It is not needed to set again the user's passwords. The workaround works simply defining 'superusers' variable into submenus.
Example:
submenu "Previous Linux versions" {
set superusers='xxuser_namexx'
menuentry 'Ubuntu, mit Linux 2.6.37-12-generic' --class ubuntu --class gnu-linux --class gnu --class os {
...
It is not needed to set again the user's passwords. The workaround works simply defining 'superusers' variable into submenus.
Example:
submenu "Previous Linux versions" { 'xxuser_ namexx'
set superusers=
menuentry 'Ubuntu, mit Linux 2.6.37-12-generic' --class ubuntu --class gnu-linux --class gnu --class os {
...