Resolution?

You can download CF Tool which allows you to change the resolution up to 1920 x 1080. Some features may not work on it as it hasn't been updated in a while but you can still change the resolution. You will need to register but it doesn't take long.

Here is the link: http://modhub.org/othermods/656-cf-tool

Faster way:
Go to "My documents" > "Crossfire" > "System" > open with notepad, now change the first number to 6.
Now you have 1920x1080

Once you go in game it will be 1920x1080 automatically, no need to change any resolutions in game.