Changing text content of slotted items does not trigger change detection

[hudson-newey]

Example

Changing the text content of a verification grids <template> after initialization will not cause the verification grid to update.

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As far as I remember, Lit provides some slotted content reactivity but lacks full reactivity support (most likely to improve performance).

At the moment our AbstractComponent acts as a reactive controller for slotted content. Listening for the slotchange event and triggering a rendering cycle.

However, listening to the slotchange event doesn't cover circumstances where the attributes / properties / text of slotted content changes.

This means that if an attribute, property or text of a slotted element is changed, we currently do not trigger a re-render, sometimes causing an outdated DOM.

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We should explore how we can make parent components update if certain attributes/properties/text content on slotted children update.

I don't want to re-render all parent components if any attribute/property/text on a slotted element updates because that could cause significant performance problems for deeply nested components.