Hide the terminals part of the running sessions status bar item by default

[jtpio]

References

Fixes #11547

As discussed in #11547, this status bar item is probably not very useful in practice. And hiding it by default would leave more space for other items.

Code changes

• Add a setting to allow for hiding the "Running Sessions" status bar item
• Hide the terminal part of the status bar item if there is no terminal running
• Update UI tests snapshots

User-facing changes

• The status bar item does not show the terminal icon and number if there is not terminal currently running
• The item can be hidden entirely from the status bar via the Settings Editor

jupyterlab-autohide-terminal-status-bar.mov

Backwards-incompatible changes

None

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[SylvainCorlay]

Awesome!

[jtpio]

Following @krassowski's comment in #11547 (comment) :

What about auto-hiding the terminals part when there are no running terminals? This would reduce the terminals + kernels item by half for many users.

This PR was updated to:

• auto hide the terminals part of the status item if there is not terminal currently running
• keep the setting, but enabled by default to not change the current behavior

And the UI tests snapshots updated accordingly.

Marking it as ready so it can be considered for 4.4.0.

[krassowski]

Wouldn't it register the item multiple times once we add more settings? I think it needs a guard to check if the disposable is defined and not disposed

[jtpio]

It looks like that would be the case. Maybe we can indeed add such guard to anticipate the case where new settings would be added 👍

[jtpio]

Or maybe we can just dispose the item, and recreate it if showStatusBarItem is true.

[krassowski]

Some minor improvement suggestions

[krassowski]

Can we return null or otherwise at least an empty fragment (<></>) here? See https://react.dev/learn/conditional-rendering#conditionally-returning-nothing-with-null

Suggested change

	<div></div>
	null

[jtpio]

Looks like the use of GroupItem prevents this:

Type 'Element | null' is not assignable to type 'Element | (Element & string)'.
  Type 'null' is not assignable to type 'Element | (Element & string)'.

[krassowski]

Thanks for checking, I've opened #17212

[krassowski]

Thank you @jtpio!

[jtpio]

Thanks @krassowski for the review!