This request is similar to #43049 but I feel it is different enough to warrant this request.

To reiterate from #43049 (comment)

While having webviews as editors is great, depending on the use-case, they can end up being the only mechanism for an extension to provide richer behaviors and interactions (think of chat integration) which can lead to a compromised experience. Because now the editor/tab needs to be managed, positioned, etc by the user.

I am currently bringing the https://codestream.com/ experience from Atom to vscode and really need to be able to provide the chat stream functionality seen here (on the right rail):

With a webview hosted in its own sidebar activity, I should be able to provide a similar (much less compromised) experience. None of the other alternatives provide anywhere close to the desired experience.

While I can definitely appreciate (and largely agree) with vscode strict api and not wanting to allow the proliferation of webviews, I would argue that allowing a single webview in a sidebar activity shouldn't really change that vs an editor -- especially since only 1 activity can be visible at a time. But it makes a huge difference to the user experience. In the example above, if the webview must be in an editor tab, it now causes lots of edge case issues, requires user positioning, tab management, etc. All of which are much less than ideal for the user.

EDIT: In addition, I would equally love it if a webview could be hosted in a (bottom) panel too.

Thanks for the consideration.

//cc @jrieken @mjbvz @lostintangent