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 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)
The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.