Wotcher TAG!

I'm requesting a TAG review of Document Picture-in-Picture.

There currently exists a Web API for putting an HTMLVideoElement into a Picture-in-Picture window (HTMLVideoElement.requestPictureInPicture()). This limits a website's ability to provide a custom picture-in-picture experience (PiP). We want to expand upon that functionality by giving websites the ability to open a picture-in-picture (i.e., always-on-top) window with a blank document that can be populated with arbitrary HTMLElements instead of only a single HTMLVideoElement.

• Explainer¹: https://github.com/WICG/document-picture-in-picture
• Security and Privacy self-review²: https://github.com/WICG/document-picture-in-picture/blob/main/security-privacy-questionnaire.md
• GitHub repo (if you prefer feedback filed there): https://github.com/WICG/document-picture-in-picture
• Primary contacts (and their relationship to the specification):
  • Tommy Steimel (steimelchrome), Google
  • Frank Liberato (liberato-at-chromium), Google
• Organization/project driving the design: Google Chrome
• External status/issue trackers for this feature (publicly visible, e.g. Chrome Status): https://chromestatus.com/feature/5755179560337408

Further details:

• I have reviewed the TAG's Web Platform Design Principles
• The group where the incubation/design work on this is being done (or is intended to be done in the future): WICG
• The group where standardization of this work is intended to be done ("unknown" if not known): unknown
• Major unresolved issues with or opposition to this design:
  • See github issues list for known problems. One notable issue is that we're still trying to figure out how to best design and specify how CSS copying works for this feature
• This work is being funded by: Google

We'd prefer the TAG provide feedback as (please delete all but the desired option):

🐛 open issues in our GitHub repo for each point of feedback