[Q] [MOD] Mod Sense 4 system apps for light text on dark background

Hi there,

Given the impact on power consumption for AMOLED displays of large white areas, it is actually surprising how the colours are chosen in Sense.

I am considering to try my hand on modding the Sense 4 base apps to white(ish?) text on black background. I found a case of contacts app or message app being modded this way for an older Sense version, but surprisingly little relevant information seems to be available.

So before I start: is this a feasible endeavour? Is there a reason why this hasn't been done yet?
Any tips to make this easier or what to watch out for (I'm new at themeing but have experience building custom ROMs and general programming knowledge)

Thanks for any info!