Occurs before a ToolTip is initially displayed. This is the default event for the System.Windows.Forms.ToolTip class.
The ToolTip.Popup event is raised whenever a ToolTip is displayed, either through an explicit call to one of the erload:System.Windows.Forms.ToolTip.Show methods or when the System.Windows.Forms.ToolTip class implicitly displays a ToolTip. This event can be canceled.
Calling properties in this event that cause the underlying window handle to be recreated, such as ToolTip.IsBalloon, will result in an exception being thrown.