Indicates if the edit sketch is stretched when one of its vertices is moved.
[Visual Basic .NET] Public Property StretchGeometry As Boolean
[C#] public bool StretchGeometry {get; set;}
Product Availability
Available with ArcGIS Desktop.
Remarks
This property determines whether or not the edit sketch is stretched proportionally when a vertex is moved. The following diagrams illustrate this point better. In both cases, the upper right vertex was moved.
Moving a vertex with StretchGeometry set to True: 
Moving a vertex with StrechGeometry set to False: 
[C#]
/// /// This routine toggles the Stretch Geometry proportional property based on the current setting.
/// This setting is available on the Editing Options General tab.
///
public void ToggleStretchGeometry()
{
//get editor extension
UID editorUID = new UIDClass(); editorUID.Value = "esriEditor.Editor";
IEditor editor = m_application.FindExtensionByCLSID(editorUID) as IEditor;
IEditProperties editProperties = editor as IEditProperties;
//switch the setting on or off based on the previous value
editProperties.StretchGeometry = (!editProperties.StretchGeometry);
}