Placeholder issue for this kind of trace. See also #4019 for the two-level Marimekko variant and #1038 for the general-purpose treemap variant.

For the purposes of keeping our issues straight, a mosaic plot looks like a more-than-two-level Marimekko plot or a more-than-two-level slice-and-dice treemap. It is used to visualize contigency tables with inputs that look a lot like parcats (i.e. rows of cases with dimensional columns and values therein):