react-spectrum

This code doesn't. It guarantees that within `useControlledState`[1], `defaultValue` is either NaN, an actual number, a number-like string, or something else that can be coerced into one[2]. If `defaultValue` is, for example, `true` or even an empty array, then the result of the expression `isNaN(defaultValue) ? NaN : defaultValue` will pass through `true` or the empty array. 1. <https://github.com/adobe/react-spectrum/blob/main/packages/%...> 2. whether one of those non-numbers is prevented from actually making an appearance at this point for other _reasons_ is a different question, but the fact remains that one making its way through is not something that would be stopped from proceeding further by the isNaN check here (Addendum to, I hope, clarify: I'll reiterate that it's the type annotations on the `useControlledState` call site p

This was an intentional choice. Repositioning when an outer element scrolls is pretty janky in some cases because scroll events don’t fire at 60fps. Also it’s not possible at all in other cases, like if the trigger goes completely out of view. We used to close the popover in this case but this caused usability problems. The new behavior of preventing scroll actually matches native platforms like macOS and helps with these issues. I get that it’s a little opinionated but it was thoroughly considered, not just done out of laziness. More details in this answer: https://github.com/adobe/react-spectrum/discussions/3802#dis...