grub 2 custom.cfg colors not all used in Advanced options

[Guy Rouillier]

1) Ubuntu MATE 21.10
2) grub 2.04-1ubuntu47
3) I use text-mode for Grub, so made the following changes in /etc/default/grub:

GRUB_TIMEOUT_STYLE=timeout
GRUB_TERMINAL=console

I then created a /boot/grub/custom.cfg with the following entries:

color_normal="light-gray/blue"
color_highlight="white/blue"
menu_color_normal="light-gray/blue"
menu_color_highlight="yellow/magenta"

I expect these colors to be used on both the initial menu showing the OS version, Advanced options, and two Memory test options; and also on the Advanced options submenu showing the list of available kernels.

4) What I'm seeing is that these colors are accurately reflected on the initial text menu. However, if I select Advanced Options to show the list of kernels, then the first three color specs are shown properly. But the last one, for the highlighted menu entry is not respected. Instead, the color_highlight combination of white/blue is used instead.

After some searching, I found a suggestion to manually update the /boot/grub/grub.cfg file to add the menu_color options to the Advanced options submenu, like so:

submenu 'Advanced options for Ubuntu' $menuentry_id_option 'gnulinux-advanced-43548515-6ad7-4cdb-b295-f880ef847d12' {

    menu_color_normal="light-gray/blue"
    menu_color_highlight="yellow/magenta"

    menuentry 'Ubuntu, with Linux 5.13.0-30-generic' ...

This does indeed produce the desired result, in that the highlighted menu item now has the desired colors. But of course these changes will be lost the next time a new kernel is installed.

Since the submenu inherits color_normal and color_hightlight from the top level menu, would be great if the menu_color_normal and menu_color_highlight were also inherited. I don't believe the submenu can be modified via custom.cfg, since custom.cfg is simply sourced from grub.cfg at the very end, after all the menu and submenu entries have been created.

[Mate Kukri (mkukri)]

I think this is something that should be reported and changed upstream: https://savannah.gnu.org/bugs/?group=grub