AccentColor, PrimaryColor and PrimaryColorDark

Is there a way to read AccentColor, PrimaryColor and PrimaryColorDark in app inventor 2? Also an extension to read them should be OK for me.

As you will see from here:
http://ai2.appinventor.mit.edu/reference/components/userinterface.html#Screen
they can only be set in the designer

The actual colours used on a device, from my experience, can be different when an app is compiled...

I did not find anything more but... it should be useful to read these properties because we could change the look and feel of an app in 5 minutes... now I need to define a set of global variables just to have the same feature. At least I hope on an extension...