Assembly: System.Web.Extensions (in System.Web.Extensions.dll)
The Visible property is overridden in the Timer class to prevent setting this property. The Visible property returns true if the client component of the Timer class is included in the Web page, even if Enabled is set to false. The Visible property returns false when it is inside a container, such as an UpdatePanel control, whose Visible property is set to false.
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
The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.