I wrote the original post in this topic, but someone on Reddit asked for instructions and since I've learned more since I wrote that post, I created a new guide to implementing both Dark Mode and classic invert mode on older Kobo devices. Here it is:
It's easy to add to the Clara HD, at least, and I imagine to others, and even if Dark Mode doesn't work (which inverts text but not images, and only within books), you can still easily get the old invert mode (which inverts both text and images and all screens everywhere). Make sure you're on the latest firmware for your device (do a sync first), then the tool you need is the version of Nickel Menu you can get here (
make sure you're using this version):
https://www.mobileread.com/forums/sh...&postcount=555
Once you've installed Nickel Menu, you'll find a new folder named \.adds\nm on your Kobo reader. Copy the file below as config-nickel-menu.txt to that folder, and disconnect your reader. It should reboot, and you'll find a new "Nickel Menu" menu icon on the various screens of your Kobo.
More about Nickel Menu is here:
https://www.mobileread.com/forums/sh...d.php?t=329525
Note: with the latest firmware, you can toggle dark mode, but on older devices, you have to close then reopen your book (or open the table of contents or the annotations listing from within the book) to make the Kobo recognize that you've switched modes, and to get the classic invert mode (text and images, and all screens, inverted), the Kobo needs to reboot itself for it to take effect (all your content will be fine); the Nickel Menu definitions I've provided do that automatically, although it takes several seconds to happen).
You can get my Nickel Menu file here:
https://sfwriter.com/config-nickel-menu.txt
Feel free to remove or comment out (by adding a "#" to the front of the line) items that are irrelevant to your usage. Not that the Nickel Menu file needs Unix/Mac style line endings (life-feed only), not DOS/Windows ones (carriage return followed by line-feed). If your file editor creates a *.BAK file, delete that when you're finished editing:
Code:
# DON'T FORGET TO ERASE *.BAK FILE
# -----------------------------------------------------------------------
menu_item :main :Dark Mode :nickel_setting :toggle :dark_mode
menu_item :main :Invert & Reboot :nickel_setting :toggle: invert
chain_success :power :reboot
menu_item :main :Portrait :nickel_orientation :portrait
menu_item :main :> Landscape :nickel_orientation :landscape
menu_item :main :< Landscape :nickel_orientation :inverted_landscape
menu_item :main :My Articles :nickel_open: library: pocket
menu_item :main :Screenshots :nickel_setting :toggle :screenshots
# -----------------------------------------------------------------------
menu_item :reader :Dark Mode :nickel_setting :toggle :dark_mode
menu_item :reader :Invert & Reboot :nickel_setting :toggle: invert
chain_success :power :reboot
menu_item :reader :Portrait :nickel_orientation :portrait
menu_item :reader :> Landscape :nickel_orientation :landscape
menu_item :reader :< Landscape :nickel_orientation :inverted_landscape
menu_item :reader :My Articles :nickel_open: library: pocket
# -----------------------------------------------------------------------
menu_item :library :Dark Mode :nickel_setting :toggle :dark_mode
menu_item :library :Invert & Reboot :nickel_setting :toggle: invert
chain_success :power :reboot
menu_item :library :Portrait :nickel_orientation :portrait
menu_item :library :> Landscape :nickel_orientation :landscape
menu_item :library :< Landscape :nickel_orientation :inverted_landscape
menu_item :library :My Articles :nickel_open: library: pocket
# --------------------------------------------------------------------------