Qwt_Slider, how to create hot spots in its scale?

[Hogwarts]

Hello!
I need help in what follows: I'm using Qwt library, specifically its slider. I need to change the backgroud color to its scale. At first, I need to know at least how to do this, so that perhaps I get to do what I really want, that is creating hot zones in the scale. I explain: I need to divide the scale into zones, matching, for example, green color to values between 0 and 60, yellow between 61-90 and so on. I'm trying to develop graphic components for a configuration editor of a SCADA. I'm using QT and Qwt. Any help is welcomed.

Thanks in advance.