Is there anyway to add an option to customize the color of the progress bar? Maybe to use class colors? TIA. :)

There are some customization options for the progress bar, such as setting textures or fonts. Colors are hardcoded right now:

It shouldn't be difficult to make them adjustable, although I don't know that class colors make sense in this case?
The thresholds are percentages towards completion, so every 33% the color changes. You could override them with a script.

Thanks for the response. I suggested class colors as my UI uses the class colors everywhere. :) Not sure how to script the color changes but I've modified the code to make all 4 steps purple for now. Thanks again. :)

The progress bar is in the process of being reworked (#891, #884, #856). I'll look into customization once that's completed.