'Declaration Public Property Orientation As Orientation
public Orientation Orientation {get; set;}
The Orientation determines how the TabGroups are laid out. The tab groups are either displayed with a Horizontal split and laid out from top to bottom or they are displayed with a Vertical split and laid out from left to right. When there is only 1 MdiTabGroup in the TabGroups collection, the end user may create a new MdiTabGroup in either orientation unless the AllowHorizontalTabGroups or AllowVerticalTabGroups is set to false.
The Orientation may also be changed programatically to switch between the layout styles. This will affect the Extent of tab groups in the TabGroups collection since the sum of the extents must match the extent of the relative client area. In other words, when the Orientation is set to Horizontal, the sum of the extents must equal the height of the client size of the mdi client. If this is not the case, the tab groups are resized proportionally based on their current extents to adjust for the difference.
Target Platforms: Windows 10, Windows 8.1, Windows 8, Windows 7, Windows Server 2012, 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