textformat problem

Hi people,

I want to have a custom selection color in an input textfield. The textfield is white text on a black background, so you can't see the selected text, because the selection color is also black.
Now I tried to change the text color of the selected text, and it's kind of working, but it uses some other colors than I want. Here's the code I used:
--
var tf1:TextFormat = new TextFormat();
tf1.font = "vera";
tf1.size = 8;
tf1.color = 0xFF0000;
var tf2:TextFormat = new TextFormat();
tf2.font = "vera";
tf2.size = 8;
tf2.color = 0x0000FF;
var mc = createEmptyMovieClip("selectionChecker", getNextHighestDepth());
mc.onEnterFrame = function() {
chat_txt.setTextFormat(tf1);
chat_txt.setTextFormat(Selection.getBeginIndex(), Selection.getEndIndex(), tf2);
};
--
As you see, the text has red color (tf1), and the selected text is supposed to change to blue (tf2). However, the selected text appears white. When I change tf1 to white and tf2 to red, the selected text stays white. What's the problem here?

greets,
blemmo