Hi,
The problem is the following:
Here I have just double clicked on the asdasdasd and it’s selected, but the color is so light, it’s hard to tell what’s selected. As I use a lot of text selecting with Shift+Arrows or Ctrl+Shift+Arrows, this brings down productivity. It’s similarly too light on a couple of other computers I tried but I’ve seen that it’s better on some other screens. Most other apps/programs/pages on the monitor in question can clearly highlight the selected text’s box so why not coda? 
Otherwise Coda rocks!
With greetings from Estonia,
Indrek