Assembly: System.Windows (in System.Windows.dll)
<ColumnDefinition Width="doubleValue"/> - or - <ColumnDefinition Width="starSizing"/> -or- <ColumnDefinition Width="Auto"/>
Dependency property identifier field: WidthProperty
If a child element is added to a column in a Grid, and the column has its property set to Auto, the child will be measured without restrictions. This behavior can prevent horizontal scroll bars from displaying if a ScrollViewer is being used, as the child element is measured as unbounded. For purposes of display, the child is clipped instead of scrolled.
For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.