Mine

this.createTextField("my_txt", this.getNextHighestDepth(), 10, 10, 100, 24);
my_txt.type = "input";
my_txt.background = my_txt.border = true;
my_txt.backgroundColor = 0xFFFF00;
my_txt.text ="qqqqq";

my_txt.onKillFocus = function() {
    this.backgroundColor = 0xFFFF00;
}
my_txt.onSetFocus = function() {
    this.backgroundColor = 0xFF0000;
}