Trying to figure out when, where, and why Tableau adds and removes containers to dashboards is an exercise in frustration. Every time I think I have a handle on it I realize that there's more going on under the hood than I see. It's really, really difficult to develop a replicable example of strange behavior, partly because so much of it feels weird and counter intuitive.
But no more. I was noodling around recently and noticed that adding the title to the dashboard was causing some strange effects. And removing it, and then adding it again, was causing more oddness.
So it didn't take much to come up with this post's scenario in which, to a brand spankin' new empty dashboard I add, remove, add, remove, then add the title. The results are shown below.
The empty dashboard:
Showing and hiding this empty dashboard's Title:
Tableau adds four components: three containers and the title – "Dashboard 1"
It's not at all clear why Tableau thinks all 3 of these containers are necessary. Any of them can be removed from the dashbord without apparent ill effect.
Tableau removes the title, leaving the three containers.
It seems reasonable to ask: why doesn't Tableau remove these containers, that it just put there? There's nothing in them, and we see in other circumstances where Tableau will remove containers.
Show Title (2nd time)
Tableau adds the Title in the same location as before, 3rd from the top, but it also adds a new Vertical container and a new Tiled container, although it's not possible to tell where they were placed.
Hide Title (2nd time)
Tableau again removes the title, leaving all of the containers in place.
The dashboard now has five completely unnecessary containers. In fact their presence is worse than unnecessary, they're an active impediment to interacting with the dashboard.
Show Title (3rd time)
Once again Tableau adds the title, in the usual position, and also adds another two containers, one Vertical and one Tiled.
The addition of extraneous containers continues. Every time the title is shown in the dashboard Tableau adds more containers.
This container proliferation is a real problem. In a "real" dashboard they get in the way, gum up the works, are sand in the gears. Their mere presence makes it harder to identify the meaningful and useful containers and other components. If nothing else, they clog up the Layout pane of the Dashboard window, rendering its relatively small size (and that's a problem in itself) even more difficult to work with.
It could be argued that there's not really much of a problem here, really. After all, who Shows, unShows, Shows, and unShows a dashboard's tile multipe times? And so Tableau adds a couple of extra containers, that's not so bad in the real world, where a normal person would add the title straight away so these "title containers" won't actually cause problems with "real" containers added later.
Those would be nice arguments, but they have no legs. Adding these containers, adding them over and over again is a real problem. It's perfectly normal to Show the Title, and unShow it, at various times during dashboard construction. And when that happens, these added containers really can be a huge cognitive barrier to effectively locating and managing the real dashboard content of interest—the worksheets and other elements that are the whole point.
Fortunately, it feels like this shouldn't be too terribly difficult a fix. Hopefully it's something that someone can work out relatively easily and get straight while we wait for a new dashboard layout management approach and implementation. Or at least for a description of the existing dashboard layout manager's behavior so we can understand how it works and develop reasoned techinques for working with it instead of flailing around trying hit-and-miss stabs in the dark to see if we can get the results we're after.