/// <summary>
/// Performs event handling of the HMouseWheel event of
/// HWindowControl, so that the dipslayed image part and scroll bars
/// of HDisplayControl can be adapted to the current zoom value.
/// </summary>
private void viewPort_HMouseWheel(object sender, HMouseEventArgs e)
{
hWndControl.mouseWheel(sender, e);
ManageScrollBars();
hWndControl.repaint();
this.Invalidate();
}