is it possible to style a textbox?

this is actually for the XUL element textbox, but if you know nothing about that imagine it as a textarea element.

The textarea displays the innerHTML of the body. I want to make syntax highlighting. I already can take the whole text and make it a different color. But how would i be able to change the color of individual things. It doesnt look like i can use html in the textbox because it displays all text.

What i dont want it to come to, is to have to not use a textbox, display the innerHTML as content, and make it editable and then put styles to that. this would suck, i hope i can do it with the textbox

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