flex toolTip样式设置

需要3个文件。一个是样式类，一个样式文件，一个是mxml文件。
●MyToolTip.as
package{
 import mx.core.UITextField;
 import mx.skins.halo.ToolTipBorder;
 import mx.controls.ToolTip;
 public class MyToolTip extends ToolTipBorder {
  
  
  override protected function updateDisplayList(unscaledWidth:Number,
   unscaledHeight:Number):void{
    
    var toolTip:ToolTip = (this.parent as ToolTip);
    var textField:UITextField = toolTip.getChildAt(1) as UITextField;
    textField.htmlText = textField.text;
    
    
    var calHeight:Number = textField.height;
    calHeight += textField.y*2;
    calHeight += textField.getStyle("paddingTop");
    calHeight += textField.getStyle("paddingBottom");
    
    
    var calWidth:Number = textField.textWidth;
    calWidth += textField.x*2;
    calWidth += textField.getStyle("paddingLeft");
    calWidth += textField.getStyle("paddingRight");
    
    super.updateDisplayList(calWidth, calHeight);
   }
 }
}
●style.css
ToolTip{
    font-family:            verdana;
    font-size:              14px;
    color:                  #000000;
    background-color:       #FF00FF;
    background-alpha:       0.85;
    cornerRa