'Declaration Public Class VisibleChangingEvent Inherits System.ComponentModel.CancelEventArgs
public class VisibleChangingEvent : System.ComponentModel.CancelEventArgs
Unlike other events on the UltraWebToolbar that provide notification of client-side activities (such as a button click or a toolbar drag) after Page_Load, the VisibleChangingEvent occurs in real-time to notify subscribers that the Visible property on a TBarButton has been modified.
This is a cancelable event. Any event handler that raises the Cancel flag on the VisibleChangingEvent arguments passed to that handler can prevent the newly assigned visibility from being accepted.
Developers may want to receive this event notification so they can reperform any necessary layout operations on the UltraWebToolbar to account for the change in the number of visible buttons it may contain.
Container classes that hold instances of TBarButton may also use the cancelation feature of this event notification to suppress changes to the Visible property of individual toolbar items if they have their own Visible property that must supercede the Visible states of their contents.
This event can only be fired when toolbar items attached to the UltraWebToolbar experience a change in their Visible property. No notice can be given when the Visible property is changed on a detached TBarButton.
Target Platforms: Windows 10, Windows 8.1, Windows 8, Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2