void docView_ZoomChanged(object sender, EventArgs e)
        {
            ZoomEventArgs zoomArgs = e as ZoomEventArgs;

            zoomManager.setCustomZoom(zoomArgs.Mode == ZoomEventArgs.ZoomMode.CUSTOM ? zoomArgs.Zoom : docView.Zoom);

            switch (zoomArgs.Mode)
            {
            case ZoomEventArgs.ZoomMode.INCREASE:
                zoomManager.increaseZoom();
                break;

            case ZoomEventArgs.ZoomMode.DECREASE:
                zoomManager.decreaseZoom();
                break;

            case ZoomEventArgs.ZoomMode.CUSTOM:
                docView.setZoom(zoomArgs.Fit, zoomArgs.Zoom);

                if (zoomArgs.Fit == FitModes.FitNone)
                {
                    zoomManager.onCustomZoomLevelSelected();
                }
                else
                {
                    zoomManager.onZoomLevelChanged(zoomArgs.Fit == FitModes.FitPage ? 12 : 11);
                }
                break;
            }
        }
        public override void MouseDown(MouseEventArgs e, System.Drawing.Point location)
        {
            ZoomEventArgs zoomEvent = new ZoomEventArgs(Control.ModifierKeys == Keys.Shift);

            docView.RequestZoom(zoomEvent);
        }