The Canvas is made of a graph of objects, each object (a Primitive) has one direct parent and a list of children (more info).
The visibility status of a given primitive is defined by its levelVisible property and the one of all its parents (direct and indirect).
If a given Primitive has its levelVisible set to false it and its children will be hidden (regardless of the levelVisibile property of the children, the hidden status takes precedence).
The properties:
levelVisible is get/set property to define the visibility at the primitive's level. Default being true.isVisible is a get only property, it defines if the primitive is actually visible or not, based on the levelVisible of this primitive and its parents.