This file, however, does not allow you to change the main editor background color, or the colors of the un-highlighted text.
Thanks largely to st.loeffler at the Google Code project site for TeXworks, I discovered that it is possible to customize the main editor colors. You need to create a custom style sheet mystyle.css using CSS mark-up. It should look like this:
QTextEdit { background-color: black; color: white; /* sets the main text color */ }
Or you can use any of the color names of values listed here.
You then need to run TeXworks with the command:
texworks -stylesheet /pathto/mystyle.css
And then you have whatever pretty colors you want. Be sure also to change syntax-patterns.txt (backing up first) to pick syntax-highlighting colors that look good with your new background-color.
There are other things you can customize this way as described here, though I haven't tested that.
The only things you can't change, at least not until they make some improvements to TeXworks, is the colors you get when you have "highlight current line" selected, or the colors used when matching brackets are found. At the moment, I just have the former turned off.
If you're feeling particularly adventurous, you can even substitute a background image for your editor screen.
QTextEdit { background-image: url('/pathto/mybackground.png'); color: white; /* sets the main text color */ }
Of course you have to be careful what you pick if you want all your text to be readable.
For example, I made a blueish/purple background with a color gradient and some other subtle effects applied by GIMP, and so my current set up looks like this:
Just thought I'd share my happiness. It's purely aesthetic of course, but it makes my day a little more pleasant.