A tool rail on the left of the stage adds channels, exposure and gamma,
zebra, histogram and waveform scopes, composition guides, aspect masks,
pixel probe, loupe, copy to clipboard and A/B compare (wipe, side by side,
difference, add, subtract, multiply, screen) with B selection, pin and
swap. Colour tools are SVG filters so they also apply to playing video;
video compare keeps a second player in sync.
3D models and the A/B / side-by-side open modes now use the Studio viewer,
audio files show a live spectrum, and the inspector's tag editor no longer
steals focus after navigating.