Expand sl-tree-item on first selection.

[grncdr]

Previously, an sl-tree with the 'single' selection mode would always toggle the expanded state of an item when selecting it, which leads to an unusual behaviour: selecting an expanded (but not previously selected) item collapses it.

This changes the behaviour of 'single' mode so that an item is always expanded when it is first selected. Clicking an item that was already selected then toggles it's expanded state.

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See related discussion in #1159

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Name	Status	Preview	Updated (UTC)
shoelace	✅ Ready (Inspect)	Visit Preview	Aug 15, 2023 11:20am

[grncdr]

I've intentionally scoped this change very narrowly, for reasons described in the linked discussion (comment).

[claviska]

I can see why this is useful. My only question is, should we identify clicks on the chevron and always toggle for those clicks and use the new behavior for clicks elsewhere on the tree item?

[grncdr]

I can see why this is useful. My only question is, should we identify clicks on the chevron and always toggle for those clicks and use the new behavior for clicks elsewhere on the tree item?

It sounds reasonable, and there's already code that detects if a click was on the chevron, so to implement I only needed to forward that boolean to selectItem. However, it reintroduces the problematic behaviour I'm trying to fix: clicking the chevron for a deselected + expanded tree item will set selected = true and expanded = false.

After clicking around a bunch on
https://shoelace-b9zozc8hn-font-awesome.vercel.app/components/tree/ I think a better option might be to combine it with #1521.

[claviska]

Thanks again for the PRs! I believe this was resolved as part of #1521, but if I'm mistaken let me know.