Update the extension examples repo to use the latest extension template

[cmarmo]

Dear maintainers,

this pull request updates the extension examples to the latest extension template.

I tried to create one commit per example as I feel it could make the review easier, don't hesitate to squash the commits if this PR is merged.

Hopefully this update will solve the failing CI in #279

Thank you for your attention.

[cmarmo]

Almost there....
In order to fix the ui-tests comparing screenshots I have replaced those in the repo with the "actual" screenshots generated during the tests. Differences were very small details perhaps related to the aliasing of the text?
https://github.com/cmarmo/extension-examples/actions/runs/16030355486

Tracking the last two failures....

[cmarmo]

Aahhhhh ... it looks like I didn´t synchronize my two branches .... sorry...

[cmarmo]

Dear maintainers, if I have synchronized correctly this branch with https://github.com/cmarmo/extension-examples/tree/test-for-update, I am still having two failures in "kernel-output" and "toolbar-button".

I dare to ask for some help there... 😞

I am unable to understand the error in
https://github.com/cmarmo/extension-examples/actions/runs/16056759942/job/45312994750#step:19:163

On the other side if I understand correctly
https://github.com/cmarmo/extension-examples/actions/runs/16056759942/job/45312994642#step:19:160
the issue is that in the kernel selection widget the text of the option contains also the id session of the kernel and I don't know how to correctly match it...

[cmarmo]

😱

[krassowski]

node_modules/lib0/encoding.d.ts(6,11): error TS2315: Type 'Uint8Array' is not generic.

I guess we need a new template version to pull jupyterlab/extension-template#107. Or to pin down the lib0 dependencies.

[krassowski]

I tagged 4.4.0: https://github.com/jupyterlab/extension-template/releases/tag/v4.4.0

[cmarmo]

Thank you @krassowski!
Yes I have updated the package.json files, as I could't succeed in update from copier.... I understand now that the tag was missing.

[cmarmo]

Don´t bother starting the CI ... I have some new failures in my test version too... 🤔

[cmarmo]

I have fixed codemirror toparea-text-widget and shout-button

[krassowski]

It looks like the codemirror test is flaky. In the recording it looks fine:

and it passed on Mac but failed (timed out waiting on await page.notebook.setCell) on Ubuntu.

I think it is an issue with galata's implementation of page.notebook.setCell - for code cells it waits for stable rendering:

https://github.com/jupyterlab/jupyterlab/blob/b4b496e9a0704da70266ade98bcd74929f15ee26/galata/src/helpers/notebook.ts#L1266-L1294

Maybe using a markdown cell in this test could help?

[cmarmo]

I think it is an issue with galata's implementation of page.notebook.setCell - for code cells it waits for stable rendering:

I guess this is the issue for toolbar-button too then (https://github.com/jupyterlab/extension-examples/actions/runs/16755565700/job/47482296812?pr=284#step:19:158).
In that case I cannot modify the cell type to 'markdown' as there is no output for markdown cells.
Should I modify galata?

[krassowski]

toolbar-button looks different, it seems like a bug with the toolbar overflowing and overlapping the cell:

As a workaround maybe we should collapse the left sidebar? There is a method for it in galata/