Used with-in a rule's conditions element to match and element's that are containers or are contained within another element. Both the container and child attributes may use variables.

Properties and Methods inherited from XUL Element

A variable reference to a node that is expected to be a child of the element that is refered to by the container element.

A variable reference to a node that is expected to be a container. If the variable is the same as the uri attribute on the content element, the resource must be a container element in order to match.