FLASH + Change color of letter in grid

I have a grid of letters, and when a button is clicked, it makes all the other letters invisible, but i would like to change the color of the actual letter inside of making all the other letter invisible

function showAnswers() {
      //this function turns off the visibility on all letters except those that belong to a word

      for (var i = 0; i<boardSize; ++i) {
            for (var j = 0; j<boardSize; ++j) {
                  var clip:String = "letter"+i+"_"+j;
                  //if dummy==true then the letter does not belong to a word, so we turn off the visibility
                  if (board[clip].dummy) {
                       board[clip]._visible = false;                  }
            }
      }
}