Page_config attribute to handle keydown event at bubbling phase

[brichet]

EDITED AFTER MERGE

The code changed in this PR was experimental and has been removed in #14115, in this commit 5c6c7d7, to avoid application instability.

INITIAL DESCRIPTION

This PR adds a new attribute to the page_config.json file, to allow handling the keydown event at bubbling phase instead of capture phase.

---

page_config.json

{
  "bubbling_keydown": true
}

See the documentation to set it up.

References

See #14115 (comment) for context.

Draft PR until jupyterlab/lumino#635 is merged and released.

Code changes

When launching the application (dev_mode/index.js), the value of bubbling_keydown (boolean) is send to the lumino Application.
If the bubbling_keydown is false or undefined, the application starts as usual.

User-facing changes

None

Backwards-incompatible changes

None

cc. @fcollonval @krassowski @gabalafou

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[fcollonval]

Ok I did not think about using the pageconfig. It indeed works without the need for a dynamic settings change in Lumino. But is it convenient enough for testing?

[brichet]

Ok I did not think about using the pageconfig. It indeed works without the need for a dynamic settings change in Lumino. But is it convenient enough for testing?

Yeah, I did not think about a dynamic flag 😄
This PR is probably useless since the dynamic flag is working. Except if we want long term testing, than it can be useful to avoid setting up the flag each time.

[fcollonval]

Thanks @brichet

[fcollonval]

I'm moving forward with this to be able to get it in an alpha release

[fcollonval]

CI failures are due to flakiness

[jtpio]

Is this a new setting that end users should be able to enable, or is it mostly for helping with #14115? Should there be a mention somewhere in the JupyterLab documentation?

[krassowski]

I think we don't know the answer yet. If we find it to work well I would not expose it to users. If we find any issues then it might be worth letting user decide. I would suggest opening an issue to come back to it before releasing 4.1.

[jtpio]

Opened #15158