I have logged it in our feedback portal by making this thread public. You can track its progress, subscribe for status changes and add your comments on the following link - feedback item.
I have also updated your Telerik points.
Currently, the possible solution that I can suggest is to invalidate RadGanttView after changing the GanttViewElement.GraphicalViewElement.TimelineStart property.
Dim count As Integer = 1Private Sub RadButton1_Click(sender As Object, e As EventArgs) Handles RadButton1.Click Me.RadGanttView1.GanttViewElement.GraphicalViewElement.TimelineStart = DateTime.Now.AddDays(count) Me.RadGanttView1.GanttViewElement.GraphicalViewElement.InvalidateMeasure(true) Me.RadGanttView1.GanttViewElement.GraphicalViewElement.UpdateLayout() count = count + 1 End Sub