Occurs when the ToolStripDropDown is opened.
Assembly: System.Windows.Forms (in System.Windows.Forms.dll)
When you create a ToolStripDropDown delegate, you identify the method that will handle the event. To associate the event with your event handler, add an instance of the delegate to the event. The event handler is called whenever the event occurs, unless you remove the delegate. For more information about event-handler delegates, see Events and Delegates.
The following code example demonstrates the use of this member. In the example, an event handler reports on the occurrence of the event. This report helps you to learn when the event occurs and can assist you in debugging. 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.
To run the example code, paste it into a project that contains an instance of type ToolStripDropDown named ToolStripDropDown1. Then ensure that the event handler is associated with the event.
Windows Phone 8.1, Windows Phone 8, Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)