fix(lemon-ui): Stop infinite re-renders of LemonTabs

[daibhin]

Problem

LemonTabs LemonTabs--transitioning is firing non-stop

Changes

Remove the prop from the hook

How did you test this code?

Clicked around and didn't seem to impact re-renders

[posthog-bot]

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[Twixes]

This is what this was supposed to fix:

LemonSegmentedButton off completely – but only in the support modal, and only on initial render. I couldn't reproduce this anywhere else, and had no idea what's going on. Only the re-render solved this. But obviously I missed that this is really bad for LemonTabs, as that uses the transitioning value properly, and LemonSegmentedButton didn't.

And naturally, in this PR the problem is back.

I looked into it deeper now and finally realized what was going on – .getBoundingClientRect(), that the hook was using, takes transform: scale(x) into account, and so the calculations were only correct once the modal appearance transition was over. That was the whole problem.

So I pushed a fix to switch to offsetLeft/offsetWidth, which solves that issue, plus added a .LemonSegmentedButton-transitioning class to animate the sliding properly.

[posthog-bot]

📸 UI snapshots have been updated

1 snapshot changes in total. 0 added, 1 modified, 0 deleted:

• chromium: 0 added, 0 modified, 0 deleted
• webkit: 0 added, 1 modified, 0 deleted (diff for shard 2)

Triggered by this commit.

👉 Review this PR's diff of snapshots.