I know creating copies of a built-in plugin or behavior is bad, I don't suggest you do it at all, but you know this a lot better than me.
Of course, creating a "text_ext" behaviour that would overwrite the draw function could do the trick too, but I have hard time finding a good way to store texts and color in the behavior parameters.
There seem to be another way though, by creating a plugin that would automatically create N text objects and manipulate himself, each text object being of one color only. This would require, for what I know, to link the 2 object types at the start of the layout (a little like this plugin
) so the "multicolored text" would know what to create. This could be impossible to propagate the Pin behavior though, no idea, you may know better.
Sorry if this didn't help, I tried my best ^^