I would like to color a shape based on 3 variables containing RGB integer values.
Should lead to a shape colored in Red
I would suggest you look into custom extensions, and by adding a graphic library to your extension you could write a service to do so (for example, opengl).
You can use style definition to define this for existing widgets. Define new style definition and then assign different RGB values while picking the color. I hope that helps!
Your answer would work if i had only a few values, but It is clearly not realistic to create 256*256*256 Styles definitions ;-)
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