It might be worth poking around the forum for records of the early days as that certainly wasn’t Vinnie’s attitude when writing vflib, which as said was largely integrated into JUCE. To integrate it to JUCE 7, you need to make modifications like unfinalizing certain low level classes for drawing, GraphicsContext, etc. I am sure the Direct2D work required similar changes. Direct2D Part Deux : 2 Direct 2 Furious
PoCs in this regard however are a lot less than that, kind of like a minimum LoC example to demonstrate a bug in current JUCE master or develop.
We have a need to work with juce_core in a very “tear it apart to get it to work in resource-constrained embedded environments” way as it is, so it’s not much more effort to play around with it.
Demonstrating an IoC paradigm for the Component system also doesn’t have to be that much work… a few subclasses on top of a rewritten juce::Component class yielding a demo that shows the advantages is all that’s needed.