Allow viewlets to migrate between panel and sidebar

[sbatten]

The goal of the PR is to allow entire viewlets to move between the sidebar and panel.

As a first step, I have created what is currently called a Pane (name can be changed) to wrap the logic surrounding Panels, ViewContainers, Viewlets, and Views. Initial limitation for v0.0 is that we assume the view container has one view as is the case with Search. I have changed Search's implementation to use the PaneRegistry to start which now is working.

We can see that the interface for the PaneRegistry is similar to other Registries in the code but it does a poor job at abstracting away the concept of Views, Viewlets, and Panels. This is because it was easier to get Search working without dropping half of its implementation.

Next steps involve making a simpler view work with an API that abstracts away the older concepts. I.e. the new view would define a single view and handle its layout accordingly instead of defining a panel and view and viewlet.

Following that, I will look into adding multiple views per viewlet.

Lastly, polishing the basic experience.

• Get a basic registry working
• Get search working in the new model
• Clean up the registry interface to abstract older concepts out
• Get a simple single view working with the new model
• Adapt Search to the simplified approach
• Allow multiple views
• Allow other views (built-in, extension contributions)
• Polish the experience

[sandy081]

My feedback on the design:

I have a basic question on the design, why are you not using ViewDescriptor and ViewRegistry which is already an abstraction for all views (in Sidebar & Panel). There is also ViewContainer which can be used for the location of ViewDescriptor. Currently only sidebar views use view descriptors. So my suggestion would be to start moving Panels using view descriptors by creating a new View Container for each panel (similar to viewlets). This can allow moving views not only across side bar and panel but also across each viewlet. It will also give infrastructure for providing custom views in panels.

Current ViewRegistry already supports moving views from one view container to another.

vscode/src/vs/workbench/common/views.ts

Line 171 in 88c2100

moveViews(views: IViewDescriptor[], viewContainer: ViewContainer): void;

Views are updated in the Viewlets when views are added/removed/moved.

As said, currently viewlets use view descriptors and the first step would be to let panels also us it.

[sbatten]

@sandy081 greet feedback, when trying to support a more generic model for custom views yesterday I learned a little more about the "purpose" of the view containers. I will try to map some of what I learned into using the existing registries and apply your suggestions.