ToolStripDropDown.Opened ToolStripDropDown.Opened ToolStripDropDown.Opened ToolStripDropDown.Opened Event

定义

在打开 ToolStripDropDown 时发生。Occurs when the ToolStripDropDown is opened.

public:
 event EventHandler ^ Opened;
public event EventHandler Opened;
member this.Opened : EventHandler 
Public Custom Event Opened As EventHandler 

示例

下面的代码示例演示如何使用此成员。The following code example demonstrates the use of this member. 在此示例中, 事件处理程序报告Opened事件的发生。In the example, an event handler reports on the occurrence of the Opened event. 此报表可帮助你了解何时发生事件, 并可帮助你进行调试。This report helps you to learn when the event occurs and can assist you in debugging. 若要报告多个事件或频繁发生的事件, 请考虑MessageBox.ShowConsole.WriteLine消息替换为多行或将TextBox其追加到多行。To report on multiple events or on events that occur frequently, consider replacing MessageBox.Show with Console.WriteLine or appending the message to a multiline TextBox.

若要运行示例代码, 请将其粘贴到包含名为ToolStripDropDown ToolStripDropDown1的类型的实例的项目中。To run the example code, paste it into a project that contains an instance of type ToolStripDropDown named ToolStripDropDown1. 然后, 确保事件处理程序与Opened事件相关联。Then ensure that the event handler is associated with the Opened event.

private void ToolStripDropDown1_Opened(Object sender, EventArgs e) {

   MessageBox.Show("You are in the ToolStripDropDown.Opened event.");

}
Private Sub ToolStripDropDown1_Opened(sender as Object, e as EventArgs) _ 
     Handles ToolStripDropDown1.Opened

   MessageBox.Show("You are in the ToolStripDropDown.Opened event.")

End Sub

注解

创建 ToolStripDropDown 委托时,需要标识将处理该事件的方法。When you create a ToolStripDropDown delegate, you identify the method that will handle the event. 若要将事件与事件处理程序关联,请将该委托的一个实例添加到事件中。To associate the event with your event handler, add an instance of the delegate to the event. 除非移除了该委托,否则每当发生该事件时就会调用事件处理程序。The event handler is called whenever the event occurs, unless you remove the delegate. 有关事件处理程序委托的详细信息,请参阅处理和引发事件For more information about event-handler delegates, see Handling and Raising Events.

适用于