Gets or sets the size of the part of the scrollable content that is visible.
Namespace:System.Windows.Controls.Primitives Assembly:PresentationFramework (in PresentationFramework.dll) XMLNS for XAML: http://schemas.microsoft.com/winfx/2006/xaml/presentation, http://schemas.microsoft.com/netfx/2007/xaml/presentation
The value of the ViewportSize property is used to calculate the size of the Thumb control in a ScrollBar when the ViewportSize is not Double.NaN. For more information, see the remarks for the Thumb property.
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)