/usr/share/cairo-dock/plug-ins/rendering/readme-3D-plane-view is in cairo-dock-rendering-plug-in 3.4.1-2build1.
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1 2 3 4 | <b>A 3D plane view</b>
This is the closest view to MacOSX's dock.
You can choose to display separators as a line
or a physical hole on the plane.
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