Ctrl+LMB-drag now enters a special zoom mode where the selected rectangle is zoomed in to cover the whole screen, and the rest of the screen is considerably dimmed down (even more so than in highlight box and spotlight mode).
This also decouples the visual zoom factor from the page resolution zoom factor; in other words, it's possible to zoom in *really* far now, even though the rendering resolution is limited to only 5x, 2x or even 1x (see new --maxzoom option).