Intent to Implement: Navigation-controls media query

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Mustapha Jaber

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Sep 12, 2019, 1:36:41 PM9/12/19

to blin...@chromium.org, Jason McConnell, John Jansen

Contact emails

mgi...@google.com,harr...@google.com,mus...@microsoft.com,joh...@microsoft.com

Explainer

https://github.com/fallaciousreasoning/backbutton-mediaquery/blob/master/explainer.md

Design docs/spec

Specification: https://github.com/w3c/csswg-drafts/issues/4187

https://github.com/w3c/csswg-drafts/issues/4187

https://github.com/fallaciousreasoning/backbutton-mediaquery

TAG review

Pending completion of Intent to implement; will link once TAG review issue is filed.

Summary

Adding ‘navigation-controls’ media feature, which will initially be used to detect if the user agent supplies a back button present in its UI. This media feature will allow apps to avoid the "double back button" problem by letting them conditionally display a back button depending on whether the user agent is already displaying one. Adding a standard way to detect navigation controls like the back button and in future other navigation controls, means that we can avoid user-agent and viewport-size workarounds, which are not ideal for web compatibility. For extended background on motivations, please refer to explainer.

Motivation

This API will help us eliminate the "double back button" problem (seen here, on Twitters PWA in the Microsoft store). This problem arises because developers of "standalone", "fullscreen", and "minimal-ui" apps have no way of determining whether navigation controls will be provided by the user agent (the browser, OS, or hardware), and so, are forced to implement their own, to ensure that their app is functional without the browser's UI.

Risks

Interoperability and Compatibility

No expected interop or compat risk.

Firefox: Public support (https://github.com/w3c/csswg-drafts/issues/4187#issuecomment-528132578)

The CSSWG discussed the proposal and resolved to add it to MQ5 spec.

Edge: Public support (https://github.com/w3c/csswg-drafts/issues/4187#issuecomment-528132578)

The CSSWG discussed the proposal and resolved to add it to MQ5 spec.

Safari: Public support (https://github.com/w3c/csswg-drafts/issues/4187#issuecomment-528132578)

The CSSWG discussed the proposal and resolved to add it to MQ5 spec.

Web developers: No signals

Will this feature be supported on all six Blink platforms (Windows, Mac, Linux, Chrome OS, Android, and Android WebView)?

Yes