Installer partition editor does not set bootable flag

[Adam Wiggins]

When installing Ubuntu I like to use the graphical partition editor to set up partitions. (I find that a / that is separate from /home is preferable, because you can easily reinstall the OS without touching user files.) This works great, except that the bootable flag is not set on the first partition. There is no place to set it that I can see ("manage flags" is grayed out on new partitions). So this means that when I reboot after reinstalling, it tells me "no bootable disc." I have to use a rescue disc and run fdisk on the partition manually to set the bootable flag.