grub-choose-default gives you a GUI that you can use to easily select the next default for grub and you can go and grab a snack while your computer reboots without having to wait for anything.
It's a very simple program that just reads your grub menu entries and then lets you click on the one you want to be the next default.
How It Works
Since grub2 reached version 1.98, setting the default boot entry through the "grub environment" is supported. From Linux, the grub-set-default command is available again, just as before with grub-legacy. Under Windows grub's code is used to edit the environment directly.
grub-choose-default is available both for Linux and Windows. It should also work on other Unices, but has not been tested (user reports are welcome).
Under Linux it reads /boot/grub/grub.cfg and sets your choice using grub-set-default.
Under Windows you need to get access to your Linux /boot. If you are running ext2/3, then you can use Ext2IFS, which gives you access to your ext2/3 partitions as regular drives under Windows. grub-set-default currently needs this and thus does not work with /boot on reiserfs or other filesystems (unless someone can point me to a similar FS driver as Ext2IFS).
Then grub-choose-default searches all your drives for boot/grub/grub.cfg or a grub/grub.cfg. The grub directory can be specified in the configuration file, which is located in the Profile folder's "Application Data" subdirectory grub-choose-default. Add the line grub_dir=D:\\grub" to the end of the file, and remember to escape backslashes.
Ending the Session
Most of the time you will want to reboot after setting the new grub entry. How to end a session is specific to the desktop environment in Linux, and in the reboot/ directory are example scripts of how to end a session. The user can install the script of his choice in $XDG_CONFIG_DIR/grub-choose-default/reboot.
Install grub-choose-default in ubuntu
sudo aptitude install grub-choose-default