It’s only available if you call the low level context object directly. Because of the specificity of the situations where it can be used, it’s more of an “expert” option, and I didn’t want to complicate the Graphics class with it.
Sure but how do you use it in Component::paint() overrides? There’s no replaceExisting parameter to Graphics::filRect(). Are you expecting users to call Graphics::getInternalContext()->fillRect(…, true)? Is this really what you want?
Nope. I’m not expecting anyone to use it for painting components, because it’s completely meaningless in any context that isn’t specifically drawing into an Image. It only makes sense to use it when you’re drawing into an Image, so it’s used in things like Image::clear().
What you’re talking about is different - you want to avoid blending in circumstances where you’re drawing a solid colour, but that’s not something that you need to set a flag to make it happen, it’s just something that the rendering code should do internally whenever possible.