The ID of the dockable window that will be placed together with this dockable window when the first time it shows up .

Namespace: http://schemas.esri.com/Desktop/AddInsSchema: DesktopAddIns_ElementOnly.xsd

<xs:attribute name="neighbor" type="xs:string" use="optional" xmlns:xs="http://www.w3.org/2001/XMLSchema"></xs:attribute>