import fl.controls.Slider;
import fl.controls.CheckBox;
import flash.display.*;

var checkBox:CheckBox = new CheckBox();
checkBox.label = "enabled";
checkBox.addEventListener(Event.CHANGE, checkBox_action);
checkBox.move(20,5);
addChild(checkBox);

var slider:Slider = new Slider();
slider.enabled = false;
slider.move(30, 40);
addChild(slider);

function checkBox_action(evt:Event):void {
    slider.enabled = checkBox.selected;
}