Comment 1 for bug 394503

I confirm this behavior, but I'm not sure it's a bug.
AFAIK, importing means adding the content of a file to the current document. That's what happens when we use File>Import AND when we open a PDF or PS (via an import dialog). But when we open a bitmap, it isn't added to the current document but opened in a new one. That's the reason why there's only a root layer.