摘自：http://www.darronschall.com/weblog/archives/000135.cfm

//复制OnRowPress，重写OnRowPress

///////////////////////////////////////////////////////////////////////////

// Double-Click Hack for List-based components
// Nov. 15, 2004 - Darron Schall

// create quick reference to ScrollSelectList's prototype
var sslp = _global.mx.controls.listclasses.ScrollSelectList.prototype;

// only run this code once.., make sure that $ oldOnRowPress is not
// defined to avoid inifinite recursion when onRowPress is called
if (!sslp.$ oldOnRowPress) {
  sslp.DOUBLE_CLICK_INTERVAL = 300;  // in milliseconds, how close two clicks must
            // be received to register as a double click
 
  // save a reference to the onRowPress function since we need to overwrite it to add
  // functionality, and we don't want to lose the original.
  sslp.$ oldOnRowPress = sslp.onRowPress;
 
  // add doubleClick event to the ScrollSelectList class
  sslp.onRowPress = function(rowIndex) {
    // if the user pressed the samw row within the time limit, fire off
    if (getTimer() - this.lastPressedTime < this.DOUBLE_CLICK_INTERVAL && this.lastPressedRow == rowIndex) {
  
      this.dispatchEvent({target:this,type:"doubleClick",row:rowIndex});
     } else {
      // not a double click - record their click time and the row selected to prepare
      // for double click
     
      // only allow double clicks under the proper conditions
      if (this.enabled && this.selectable) {
        this.lastPressedTime = getTimer();
        this.lastPressedRow = rowIndex;
       } else {
        // not really necessary, but just in case.. make sure
        // doubleClick doesn't accidentally fire
        this.lastPressedTime = 0;
        this.lastPressedRow = -1;
       }
     
      // invoke the old method that we just overwrote - using apply to get the scope correct
      this.$ oldOnRowPress.apply(this, [rowIndex]);
     }
   };
}
delete sslp;

list.dataProvider = [{label:"test"},{label:"test2"},{label:"test3"}];
list.addEventListener("doubleClick", mx.utils.Delegate.create(this, onItemSelected));
function onItemSelected(eventObj) {
   // do something with the selected item
  trace(eventObj.row);
 //trace(sslp.onRowPress)
}