By default, a cell spans across only one column, typically having the same PreferredWidth as that column. The ColumnSpan property makes it possible to support horizontal cell merging, whereby one cell can appear to span across two or more columns. For example, consider a grid with 3 columns, A, B, and C. If the developer wants the cell in position A to extend to the left edge of cell C, effectively skipping cell B, the ColumnSpan property of cell A would be set to 2.
In addition to setting the ColumnSpan property, the PreferredWidth property must also be set to an appropriate value in order to make a cell span across multiple columns. Using the example above, the PreferredWidth of cell A must be set to (A.PreferredWidth + B.PreferredWidth) in order to make it span to the left edge of cell C.
The default value of zero logically represents a span of one column.
Target Platforms: Windows 10, Windows 8.1, Windows 8, Windows 7, Windows Server 2012, 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