It allows arranging elements of a scene into named and colored "groups", that can be individually displayed or hidden.
8 layers of fixed color are available, named
7 by default. The object's color is visible on the edges of its limits when unselected.
Objects are created in the layer
0 by default.
Edit layer names
To change the name of a layer, click on the pencil icon next to the "layer" submenu title.
It switches the interface in edit mode: selecting a layer's name allows you to type in the textbox.
When you're done editing names, click on the icon again to exit the edit mode.
Set layer visibility
To hide a layer, click on the corresponding colored dot in the first row of the layer's list.
Make the layer visible again by clicking in the same spot.
Hidden layers are not rendered.
Set layer for new objects
A light gray on a layer name shows the current layer for new objects.
To change it, click on a layer name (out of name edit mode).
Set layer for selected objects
To change object (or groups) layer membership, select one or more element, and in the layers list, click on the third row of the chosen layer.