在事件委托上使用 - =时，System.ArgumentException未处理？

Question

我有这样的代码：

public void setPanelHalfHorizontalScreen(Panel p) 
     { 
      if (p != null) 
      { 
       p.Width = Screen.PrimaryScreen.Bounds.Width/2 - 2; 
       this.panelsForHalfScreen.Add(p.Name, p); 

       // http://stackoverflow.com/questions/2261828/does-an-event-gets-executed-twice-if-callback-was-assigned-twice-to-the-object 
       this.form.Resize -= new EventHandler(form_Resize); // error raised on this line: ArgumentException was unhandled 
       this.form.Resize += new EventHandler(form_Resize); 
      } 
     } 

     void form_Resize(object sender, EventArgs e) 
     { 

      foreach (DictionaryEntry p in panelsForHalfScreen) 
      { 
       this.setPanelHalfHorizontalScreen((Panel)p.Value); 
      } 
     } 

我怎样才能解决这个问题？

编辑 alt text http://img519.imageshack.us/img519/3352/bb4u.jpg

Answer 1

你确定这条线不会抛出ArgumentException的？

this.panelsForHalfScreen.Add（p.Name，p）;

原因Add方法引发的ArgumentException如果键已经在哈希表