ftd document is rendered with a top-level container initialized. This
top-level container is an
ftd.column, it places its
children on top of each other.
ftd also has a concept of
current container. When the document starts, the top
level container is set as the current container.
When a “container component” is initialized, with no children specified as
sub-sections, it becomes the current container, and all future components are
placed in it.
We can set the current container to any container using that container’s
property. The default top-level container can be set using
Read more about it in the container management guide.