Focus text field after clicking SelectAll icon button

[xuanswe]

Description of what this PR is changing or adding, and why:

In the example, when user click SelectAll icon button, the controller.selection is updated, but the focus is moved to the SelectAll icon button. Because of that, user doesn't see the selection visually. If the text field is focused again, user will see the selection.

Issues fixed by this PR (if any):

PRs or commits this PR depends on (if any):

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[sfshaza2]

It looks good to me, but I'm going to complete the website build before having a DRE approve. Thanks for this PR!

[sfshaza2]

/gbcrun

[sfshaza2]

@xuanswe, it looks like you didn't update the code excerpts in your PR. Can you do so?

As explained in the README file, when you update code on the site, you must run the refresh code excerpts tool:

"To resolve this error and update the Markdown snippets to match,
from the root of the website directory,
run ./dash_site refresh-excerpts."

And then update the PR.

[xuanswe]

@xuanswe, it looks like you didn't update the code excerpts in your PR. Can you do so?

As explained in the README file, when you update code on the site, you must run the refresh code excerpts tool:

"To resolve this error and update the Markdown snippets to match, from the root of the website directory, run ./dash_site refresh-excerpts."

And then update the PR.

Thanks for reviewing the PR.

Currently I don't have a linux environment to run the bash file. Instead, is it ok if I manually update the file https://github.com/flutter/website/blob/main/examples/ui/actions_and_shortcuts/lib/copyable_text.dart?

Otherwise, it would be nice if you could help me complete the missing step.

[sfshaza2]

/gcbrun

[flutter-website-bot]

Visit the preview URL for this PR (updated for commit 2422cc7):

https://flutter-docs-prod--pr12408-patch-1-jl97rfbe.web.app

[sfshaza2]

lgtm. @khanhnwin, the code passes the build, but does this look ok to you?