1. What is the GRUB hidden menu change?
The main motivation for adding this is, to get to a fully flickerfree 4 boot.

2. How to enable hidden GRUB menu?
On new Manjaro v18.0 installs this will be enabled by default. If your system has been upgraded to v18.0 from an older release, you can enable it by running these commands:

install linux418 or linux419: pamac install linux41[x]
check that you have quiet loglevel=3 rd.systemd.show_status=auto rd.udev.log-priority=3 in /etc/default/grub under GRUB_CMDLINE_LINUX_DEFAULT or GRUB_CMDLINE_LINUX and remove any background settings configured there.
sed -i -e 's|fsck||g' /etc/mkinitcpio.conf and pamac install systemd-fsck-silent
sudo mkinitcpio -P
sudo grub-editenv — set menu_auto_hide=1
sudo update-grub
reboot your system

Note the grub-update will overwrite any manual changes you’ve made to your grub.cfg (normally no manually changes are done to this file).

If your system has Windows on it, but you boot it only once a year so you would still like to hide the GRUB menu, you can tell GRUB to ignore the presence of Windows by running:

sudo grub-editenv — set menu_auto_hide=2

3. How to disable hidden GRUB menu
To permanently disable the auto-hide feature run:

sudo grub-editenv — unset menu_auto_hide

That is it.

4.How to access the GRUB menu when hidden
If for some reason you need to access the GRUB menu while it is hidden there are multiple ways to get to it:

While booting keep SHIFT pressed, usually you need to first press SHIFT when the vendor logo is shown by the firmware / when the firmware says e.g. “Press F2 to enter setup” if you press it earlier it may not be seen. Note this may not work on some machines.

During boot press ESC or F8 while GRUB loads (simply press the key repeatedly directly after power on until you are in the menu).

Force the previous boot to be considered failed:

Press CTRL + ALT + DEL while booting so that the system reboots before hitting the display manager (lightdm, gdm, sddm)

Press CTRL + ALT + F6 to switch away from your display manager, followed by CTRL + ALT + DEL.

Press the power-button for 4 seconds to force the machine off. Either of these will cause the boot_success grub_env flag to not get set and the menu will show the next boot.

Manually set the menu show once flag by running: «grub-set-bootflag menu_show_once» This will cause the menu to show for 60 seconds before continuing with the default boot-option.

4. When is a boot considered successful?
The boot_success grub_env flag gets set when you login as a normal user and your session lasts at least 2 minutes.

So if you e.g. login, do something and then within 30 seconds type reboot in a terminal (instead of doing the reboot from the menu) then this will not count as a successful boot and the menu will show the next boot.