void searchLookUpEdit1_Popup(object sender, EventArgs e) { 
    IPopupControl popupControl = sender as IPopupControl;   
    LayoutControl layoutControl = popupControl.PopupWindow.Controls[2].Controls[0] as LayoutControl; 
    SimpleButton Button = ((LayoutControlItem)layoutControl.Items.FindByName("lciButtonFind")).Control as SimpleButton;
    if (Button != null)
      { Button.Click -= new EventHandler(button_Click); 
        Button.Click += new EventHandler(button_Click); 
      } 
 } 
  void button_Click(object sender, EventArgs e)
 { //your code 
  }
  void searchLookUpEdit1_QueryCloseUp(object sender, System.ComponentModel.CancelEventArgs e) 
{ 
    IPopupControl popupControl = sender as IPopupControl; 
    LayoutControl layoutControl = popupControl.PopupWindow.Controls[2].Controls[0] as LayoutControl;
    SimpleButton Button = ((LayoutControlItem)layoutControl.Items.FindByName("lciButtonFind")).Control as SimpleButton;
    if (Button != null)
      {
          Button.Click -= new EventHandler(button_Click); 
      } 
}

还有一种写法

Paste_Image.png