How to Unhide the Grub2 boot menu

Although I've been using it for more than a year, Grub2 still throws up a few surprises.
OK, Grub2 tries to make things easy and automated. As an example, if update-grub doesn't find more than one OS, it assumes that you don't need the menu to show up so it becomes hidden.
Problem is that OSes that Grub2 doesn't "see" and are added as custom additions DON'T make the Grub2 boot menu "unhide".
For example, I had set up Ubuntu and Haiku on my little EeePC-901. Both OSes appear in my menu with Haiku having been added by editing /etc/grub.d/40_custom as detailed here.
As outlined here, the solution is to modify the /etc/default/grub file, specifically by
i) commenting out the line GRUB_HIDDEN_TIMEOUT=0 and
ii) ensuring you have a positive integer in the line GRUB_TIMEOUT="5"

After you've made these changes and saved the /etc/default/grub file, you MUST run update-grub for the changes to have effect.