OpenFL TextField border bug

Main.hx

package;


import openfl.display.Sprite;
import openfl.events.TimerEvent;
import openfl.text.Font;
import openfl.text.TextField;
import openfl.text.TextFormat;
import openfl.utils.Timer;

class Main extends Sprite {
	
	private var _format:TextFormat;
	private var _textField:TextField;
	private var _timer:Timer;

	public function new () {
		
		super ();

		graphics.beginFill(0x0);
		graphics.drawRect(0, 0, 800, 800);
		graphics.endFill();
		
		_format = new TextFormat ("Katamotz Ikasi", 30, 0x7A0026);
		_textField = new TextField ();
		
		_textField.defaultTextFormat = _format;
		_textField.embedFonts = true;
		_textField.selectable = false;
		_textField.background = true;
		_textField.backgroundColor = 0x0;
		
		_textField.x = 50;
		_textField.y = 50;
		_textField.width = 200;
		
		_textField.text = "Hello World";
		
		addChild (_textField);
		

		_timer = new Timer(200);
		_timer.addEventListener(TimerEvent.TIMER, changeTextColor);
		_timer.start();
	}
	
	private function changeTextColor(event:TimerEvent):Void {

		var color:UInt = 0xFFFFFF;

		if (_timer.currentCount % 2 == 0) {
			color = 0x7A0026;
		}

		_format.color = color;

		// The below lines cause the buggy behavior
		// Either of them causes the issue
		// Comment them in/out to reproduce
		_textField.defaultTextFormat = _format;
		_textField.setTextFormat(_format);
	}
}