Okay, it has been suggested that I post an answer detailing how to change the colors.txt file. It's not the solution people really want, but it is the solution available.
The first step is to find the file. It is in the data\init folder under the main dwarf fortress folder. So the path will look something like [somestuff]\Dwarf Fortress\data\init\colors.txt if you are on Windows, and something like [somestuff]/df/data/init/colors.txt if you are on Linux.
Make a backup copy of your colors.txt file. Then open the main copy (not the backup) in your favorite text editor. (NOT word processor. notepad.exe will do on Windows. I often use gedit on Linux.) You will see that it contains a number of lines that look like [ALLCAPSCOLORNAME_R:134], with an R, G, and B line for each color name. You can use these to set the red, green, and blue color values respectively for each color name. (If you need some more information about the RGB color scheme look here, or Google will have lots of results). The values must be in the range 0 to 255 inclusive. (0 and 255 are allowed, -1 and 256 aren't) 0 is minimum intensity, or none of that component. 255 is maximum intensity, or as much of that component as possible. So really bright red is specified in the file as:
Since you want better contrast between the highlighted and non highlighted lines in the menus you want to change the values of the appropriate colors so that they have more contrast. I will admit that I have no problem seeing them as is (so long as my monitor's brightness is turned up), so I cannot give too much help on selecting colors. I will suggest changing the the color balances some to help the eye pick out the difference. (For example decrease the blue and increase the red on one color while increasing the green on the other color in the pair.)
This process is somewhat complicated by two facts. One is that this will change the colors of all the things in the game, not just the menus. So if you change the DGRAY color values the color of all your metalsmiths and furnace workers will also change.
The second fact is that the menus do not use a consistent set of colors. You will need to change many colors to get all the menus.
The menus that I have checked so far are:
- The startup menu in the first screen, WHITE on DGRAY.
- The menus in the embark selection screen, as shown in the screenshot with the question, WHITE on LGRAY.
- The building material selection menu, YELLOW on BROWN
- The stocks menu, WHITE on LGRAY, with various colors in the right hand column (LGRAY, DGRAY, WHITE, YELLOW, MAGENTA, BROWN, RED) depending on how many and the state (Forbid, dump, none, etc.) of the objects in question.
- The plants and animals menus (Also available from the status-screen (z)) are LGREEN on GREEN.
- The stone menu is LGREEN on GREEN, and LRED on RED, depending on the state of the kind of stone.
- The workshop task selection menu is WHITE on LGRAY.
- The (b)uild menu is WHITE on LGRAY.
- The menus in the military screen seem to be LCYAN on LGRAY.
- The stockpile manipulation menu uses a GREEN background to show the selection, and WHITE to show active items and LGRAY to show inactive items.
- The hauling menu seems to be WHITE on LGRAY, with DGRAY to mark diabled options.
- The nobles menu is LCYAN on CYAN with more information in the colors of the second column.
- The labor menu uses DGRAY, LGRAY, WHITE for none, some, all respectively.
- The look command uses the light and dark versions of various colors depending on what is looked at.
All in all I would say that making sure it's easy to differentiate between DGRAY, LGRAY and WHITE is the most important consideration. Experiment some with the colors, and when you find a set that works for you, make a backup of the new colors.txt as well, so that you can just drop it into new installs instead of having to do the whole process over.
Hopefully this is of some use even if it's not the best solution.