Have you tried sorting the dimension? Right click on it and select Sort... then sort however you'd like to see it.
Hope this helps!
I haven't found that possible with treemaps, is there something I'm missing? For the bottom-most dimension on the Marks Card, all I've seen is that the the layout of the rectangles in the treemap is completely controlled by the descending sort of the Measure on Size.
That's correct. I was thinking of the issue differently. I was imagining a dimension on the rows or columns shelf, breaking the tree maps down into smaller segments.
I'm pretty sure that order is not preserved. The basic idea is that it's a structure with a starting node, branches, and leaves mapped to a 2-D space. It's going to emanate from larger values to smaller, from trunk to leaves.
There are different treemap algorithms. I was just over on the Google Code Playground for the Google Charts API for their treemap. The behavior is similar to Tableau and they both might have implemented the same algorithm, presumably, because it's the visual, best practice at least for now.
Because of this characteristic of treemaps not preserving order, I never include a year-range slide with them.