fix: make on first tab cycle back to last tab

[Pranav2612000]

What it does

Fixes #11746

Before this commit, trying to cycle back to the previous tab, when you were on the first tab had no action. The expected behaviour was to have the last tab in focus. This was because trying to move back from the first tab was thought to be an action of moving to the previous tab group. This commit fixes that issue by treating it as a same tab group action, and redirecting the user to the last tab in the same group.

How to test

• confirm that View: Show Previous Tab on first tab no longer cycle to last tab #11746 is fixed
• confirm there are no regressions with fix: return focus to least recently active tab #10533 #10685

Review checklist

• As an author, I have thoroughly tested my changes and carefully followed the review guidelines

Reminder for reviewers

• As a reviewer, I agree to behave in accordance with the review guidelines

[Pranav2612000]

@colin-grant-work Can you take a look at this PR when you have time

[vince-fugnitto]

Thank you for your contribution 👍

In order to accept your changes please be sure to sure to sign the eclipse contributor agreement (eca) with the same email as your authorship.

[Pranav2612000]

I've signed the agreement. Thanks for also updating the issue description. I'll keep it in mind in the future.

[vince-fugnitto]

Thank you for the contribution 👍 I confirmed that:

• cycling available tabs in a group using view: show previous tab works as expected (#11746)
• closing a tab in a different group will preserve the currently opened tab (#10865)

I'd like to get the feedback of others before merging to see if any regressions are present, but it may take a bit of time since they are at the EclipseCon 2022 conference this week.

[perrinjerome]

thank you @Pranav2612000 I hope this can make it for the next release

[vince-fugnitto]

I believe that @colin-grant-work reviewed the pull-request and noticed issues with the approach, the previous tab command would always switch to an adjacent tab, and not respect the precedence of which tab was last focused.

[Pranav2612000]

I thought this was the expected approach. Can you help me with the exact reproduction so I can fix it.

[vince-fugnitto]

@Pranav2612000 I believe that @colin-grant-work expressed an oddity with this approach but I'll let him comment further when he's back. As for now I think it does improve the situation and has value.

[colin-grant-work]

The oddity relates not so much to this case as what happens when we close views and invoke activatePreviousTabBar. In that case, the tabbar that is activated is always adjacent to the current tabbar, whereas in VSCode the tabbars are prioritized by recency. I will make a separate issue for it.