Reuse "Colors & Legend"Properties Panel on custom extension?

[ForgotMyOldUsername]

I can find 100's of hacky workarounds building theme values into arrays etc., but I can't find if it's possible to simply just use the existng default colour panel? 

I've tried just referencing it like the others, but that just breaks things.

I was hoping to keep a vanilla  look and feel with the custom extension I'm building, rather than having to reinvent the wheel 🙂

[ForgotMyOldUsername]

Has anyone managed to do this yet? 

I thought I might be able to use the current theme API, but that fails to load anything:

https://help.qlik.com/en-US/sense-developer/May2021/Subsystems/APIs/Content/Sense_ClientAPIs/Capabil...

Surely there's a simple way to reference  

A :  Default  / Current theme colours swatches
B :  Default / Current Theme Palettes ( 12 / 100 Colour version ) 
C :  Default / Current Theme Gradients colours for measure
D : Apply a colour expression from a Properties Panel variable