How to disable context menu for vertical scrollbar in WinForms GridControl?

this.gridControl1.ShowContextMenu += gridControl1_ShowContextMenu;
void gridControl1_ShowContextMenu(object sender, Syncfusion.Windows.Forms.ShowContextMenuEventArgs e)
{
    Point c = this.gridControl1.GridPointToClient(e.Point);
   //Comparing the point for vertical scroll bar
    if (this.gridControl1.ClientRectangle.Width < c.X)
    {
        //context menu has been handled
        e.Cancel = true;
    }
}

AddHandler Me.gridControl1.ShowContextMenu, AddressOf gridControl1_ShowContextMenu
Private Sub gridControl1_ShowContextMenu(ByVal sender As Object, ByVal e As Syncfusion.Windows.Forms.ShowContextMenuEventArgs)
    Dim c As Point = Me.gridControl1.GridPointToClient(e.Point)
    ‘Comparing the point for vertical scroll bar
    If Me.gridControl1.ClientRectangle.Width < c.X Then
        'context menu has been handled
        e.Cancel = True
    End If
End Sub