AlertWindow::addTextBlock(const AttributedString &);

How about it? :)

What’s a “text block” when your parameter is an AttributedString?

Also, an AttributedString needs to be pained/is not a Component - you might as well just pass a custom Component wrapping such an object…

Well, there's already an addTextBlock component, it just takes a regular string and doesn't let you control the colour (there's no colourid).  So it's  bit redundant. 

But agree, I can wrap it all up in a trivial component.