public override void OnMouseDown(int Button, int Shift, int X, int Y)
{
//Create a point in map coordinates
m_Point = m_HookHelper.ActiveView.ScreenDisplay.DisplayTransformation.ToMapPoint(X, Y);
//Start capturing mouse events
SetCapture(m_HookHelper.ActiveView.ScreenDisplay.hWnd);
m_InUse = true;
}