Change systemwide theme color

I wonder if it would be a good idea to give the users a way to easily define the systemwide theme color. I like the design of the app, but really not a big fan of its default dark theme color.

I also tried a few themes from Marketplace, but they all have flaws. Some of them don’t change settings menu color and some of them don’t match PDF background color…etc.

I wonder if someone could help me find a way to change it as a workaround for now.