A3 background colours on faders etc.

I'm having problems with eye strain working in Ardour 3 due to the low contrast between the gray
backgrounds on faders, clocks, plugin areas etc. and what appears on the foregrounds. Some of
these can be changed in the theme manager, but others can't. Is it possible to edit a file
to change all these backgrounds from mid-gray to black? If I have to hard code it and recompile,
that's an acceptable solution to me. 

To save time is anyone able to point me towards which files need editing?

BTW I have a colour blind colleague who finds this to be a worse problem than I do. He doesn't
have the same problem with Ardour 2.

John