Tabs, which represent Documents within a TabbedView, can be pinned at runtime. Pinned tabs are placed before unpinned ones. A pin-able tab displays the Pin Button next to its Close Button (see the figure below).
The IDocumentDefaultProperties.AllowPin property, accessible via the Document.Properties object, specifies whether the current Document can be pinned. To enable or disable this feature for all Documents within a Tabbed View, use the AllowPin property instead, which has a lower priority than the IDocumentDefaultProperties.AllowPin property.
Use the Document.Pinned property in code to pin/unpin individual tabs.