Public ReadOnly Property ChildControl As Control

Dim instance As ChildControlEventArgs
Dim value As Control
 
value = instance.ChildControl

public Control ChildControl {get;}

private void fpSpread1ChildControlActivated(object sender, FarPoint.Win.Spread.ChildControlEventArgs e) 
{ 
   if (e.ChildControl.Visible == false) { 
       e.Cancel = true; 
   } 
}

Private Sub FpSpread1ChildControlActivated(ByVal sender As Object, ByVal e As FarPoint.Win.Spread.ChildControlEventArgs)
    If e.ChildControl.Visible = False Then
       e.Cancel = True
    End If
End Sub