Make the initial view in flutter previewer easier to understand

[mit-mit]

flutter previewer should default to showing a more restricted, easier to understand set of nodes, for example just build methods / methods that return a Widget.

I suggest we control this via a toggle in the tool bar, for example 'Show only UI nodes' that is defaulted to on.

cc @devoncarew

[devoncarew]

We could also look into look into eliding - but still showing the top-level of nodes - in the tree ([ ] ... (21 nodes hidden)). Not sure how that would work in practice. I'd mostly want to make it very clear and obvious that we weren't showing some content. I think a very real risk is that many users won't every know that we're excluding info.

/cc @scheglov and @InMatrix

[InMatrix]

I can't really understand the problem without seeing some screenshots.

[devoncarew]

To update - we have a filter toolbar action, which we can use to evaluate the two options (showing the full file ast vs. just widget nodes).

[InMatrix]

@devoncarew Great. We should discuss what we need to measure before this filter ships in the next version.

[mit-mit]

@devoncarew what did you guys decide here? My personal preference is still to default to widget only.

[devoncarew]

There's a toggle currently (not yet released?) on the toolbar. When on, it only shows widgets and nodes that have widgets as children. It's defaulted to off, but should give us the tools to either get feedback or to do informal studies. (my personal preference is to show everything, but happy to change it if further data shows widgets only is preferred).

[mit-mit]

I thought we had data suggesting a very small percentage of users use outline view (i seem to recall 8%), and thus that seems to suggest we optimize for Flutter widget use cases rather than trying to also be a code outline view?

[devoncarew]

We do have that data, but I still have concerns about hiding data from the user by default, w/o them being aware of it. I was hoping some sort of A/B test would help get us clarity. Perhaps worth an in-person discussion.

[InMatrix]

From today's demo, I think some styling can be used to make the build method tree stand out from the rest of your code.

[mit-mit]

I also made some comments over in #1932 (comment)

[scheglov]

@InMatrix We already show build methods in bold. Is there anything also we could do to highlight them?

The data we have about standard Structure view is flawed, we record usage only when the view is focused. But this view is "used" by looking and sometimes double clocking to immediately navigate to a new element, and lose focus again.

Anyway, we now show only widgets by default, and send analytics to track the state users use it with.