Hello I did a quick search and did not find anything sorry if I over looked it.
I saw a video on how to do this but the size was not given. Here is what I want to do on the slider where it says slide to unlock on whatever you have the text is in a gray color and a white type color rolls over it making it look cool. What I want to do is change the white color so it rolls over the text in a different color ie red. What size png file do I make the color bar or whatever you want to call it? I think what it is called is the text highlight mask.
Made it easy for you. Attached is my slider theme. Mine is purple, blue and pink.
Just download the theme. Go through a couple layers of folders, find the PNG file. Change the file to whatever color you want and then SSH the theme into your phone and pick the theme in winterboard.