Try handling the this.gridGroupingControl2.TableControl.SizeChanged event. There you can use the above property to tell when the VScrollBars comes and goes.
private bool oldVScroll = false;
private void TableControl_SizeChanged(object sender, EventArgs e)
{
if(oldVScroll != this.gridGroupingControl2.TableControl.VScroll)
{
Console.WriteLine("vscrollbar: {0}", this.gridGroupingControl2.TableControl.VScroll);
}
oldVScroll = this.gridGroupingControl2.TableControl.VScroll;
}