I played around with it some more and decided that in addition to the list of things in my previous comment that I had some very specialized requirements. To really do everything that I needed I really needed my own custom widget. So I now have a very modified version of your widget that is very specific to my needs and does everything that I need. I am sure it will need some additional tuning up as I move forward with it but this is a big improvement over the QwtThermo widget I have been using. I hope you don't mind that I used your code as a base for my widget. I will give you full attribution. I would give you a copy of it but most of the features that I needed are basically hard coded rather than being configurable. For example the scale has been totally removed rather than making it so the user can turn it on and off since I don't need this in my app. So in it's current state is not suitable for anyone else to use. I think the only change I made that is something you would want it to add the ability to configure the color of the gauge. That was simple to do but if you want I could get you some code fragments to add this to your version.

I just downloaded your widget to have a look. I need a widget like this for my project and we are currently using the QwtThermo widget. This is working OK but I am not totally happy with it and I was hoping that perhaps your widget would be a better fit. Here is what I need. 1. I need to be able to turn off the scale since for my use it is meaningless and waists too much space. 2. I need to be able to control the color of the gauge since this is used to convey information to the user about what the gauge is connected to. 3. Even with the scale turned off I need to be able to somehow tell the user where the middle of the gauge is. That is the goal for the user is to adjust a control until the gauge is centered. I also need to be able to set the color of of this indicator so that I can pick a color that contrasts well with the background color. I would also like to be able to have the center maker appear on each side of the gauge. 4. I need to be able to control the width of the widget since I need a thin but tall gauge. I also notice when I set the min Value to -100 that the scale stops at -80. So this appears to be a bug. Actually it looks like the scale is offset from the zero point.