protected void Gc_MouseLeave(object sender, GLMouseEventArgs e)
        {
            if (currentmouseover != null)
            {
                currentmouseover.MouseButtonsDown = GLMouseEventArgs.MouseButtons.None;
                currentmouseover.Hover            = false;

                var mouseleaveev = new GLMouseEventArgs(e.WindowLocation);
                SetViewScreenCoord(ref e);

                if (currentmouseover.Enabled)
                {
                    currentmouseover.OnMouseLeave(mouseleaveev);
                }

                currentmouseover = null;

                ((GLControlDisplay)this).SetCursor(GLWindowControl.GLCursorType.Normal);
            }
        }