Operations are done using drag&drop. Logical layers can be moved between
physical layer groups by grabbing the layer name and dropping them in another
group on the right side. Copper layer groups can be created or removed by
grabbing the buttons from the bottom and dropping them on the stackup on the
left side.
The cross section view can be invoked on the GTK HID from the left side
layer selector (left click, Grouping), or from the preferences window
(layers tab).