[Enhancement]: Missing option to revert "Custom Theme" to default && Maybe add popular desktop theme colors to settings?

[Trucido]

OS: Windows 10 Version 1709 (OS Build 16299.334) (Also some suggestions below for Linux)
GPMDP: Version 4.5.0 https://chocolatey.org/packages/GPMDP

Issue(s):

• Missing option to revert Custom Theme back to default after choosing a custom color.

Details:

• On new installations choosing Custom Theme under Desktop Settings->Custom Theme will default to dark with your Windows accent color (usually blue #0078D7 or 0,120,215).
  I'm not sure if this is intended behavior but I like that "feature" but after choosing any theme highlight color there is no option to reset to default, or option to use your Windows accent color.

Expected behavior:

• Unchecking Custom Theme box and checking it again should reset to default?

Enhancement(s)/Suggestion(s)/Solution(s):

• Option to use Windows accent color? Or add the standard Windows color codes under a sub-menu of sorts? Or just reset it upon unchecking and rechecking the box.
• On Linux we could do something similar to provide Adwaita pastel colors and/or other popular desktop theme colors? (Ambiance, Arc, Adapta, Breeze, etc...) Or implement native GTK theme if not already implemented. Most *nix desktops theme chrome/chromium decently with GTK theme chosen under settings.

P.S. Unrelated but regarding theme issues already reported: perhaps looking at some of the css and other styling code in Play Midnight For Google Play Music extension might help finding ways to fix some of theme issues (It's an often occurrence whenever Google changes stuff it seems.).
Webstore URL: https://chrome.google.com/webstore/detail/play-midnight-for-google/ljmjmhjkcgfmfdhgplikncgndbdeckci
(If it would help organize the issue tracker, I can open another issue regarding this or reply to one of the existing ones)

P.S.S. And thanks for the great app and theme support, GPMDP restores a lot of functionality I miss from the dozen or so discontinued/abandoned Chrome extensions I've used in the past. Maybe in the future I can contribute to GPMDP :)