It would be nice to have an option for the background color of the windows (menu's, borders, and ribbon) to be darker. When working on cad for long periods of time I have found it causes eye strain when there are bright colors for the cad system. In the past, a long long time ago in a galaxy far far away.... I used to use AutoCad. I set the background to black and all the menus, and borders. Then I even had the text in the menus a grey, and everyone working in the engineering department asked me to set theirs up the same.
The only brighter colors were on the model, where you need to see whats going on.
My specific request would be for Creo to have those colors customizable, or at the very least, choose themes like Windows.