Ensure PopoverPanel can be used inside <transition> (#1653)

* ensure there is an animatable root node

This is a bit sad, but it is how Vue works...

We used to render just a simple PopoverPanel that resolved to let's say
a `<div>`, that's all good. Because the native `<transition>` component
requires that there is only 1 DOM child (regardless of the Vue "tree").
This is the sad part, because we simplified focus trapping for the
Popover by introducing sibling hidden buttons to capture focus instead
of managing this ourselves.

Since we can't just return multiple items we wrap them in a `Fragment`
component.
If you wrap items in a Fragment, then a lot of Vue's magic goes away
(automatically adding `class` to the root node). Luckily, Vue has a
solution for that, which is `inheritAttrs: false` and then manually
spreading the `attrs` onto the correct element.

This all works beautiful, but not for the `<transition>` component...
so... let's move the focus trappable elements inside the actual Panel
and update the logic slightly to go to the Next/Previous item instead of
the First/Last because the First/Last will now be the actual focus guards.

* update changelog

* make TypeScript a bit happier

* improve `default` slot in `PopoverPanel`

packages/@headlessui-react/src/test-utils/interactions.ts

@@ -234,7 +234,7 @@ export async function click(
 ) {
   try {
     if (element === null) return expect(element).not.toBe(null)
-    if (element.disabled) return
+    if (element instanceof HTMLButtonElement && element.disabled) return
 
     let options = { button }
 

packages/@headlessui-vue/CHANGELOG.md

@@ -17,6 +17,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Fix getting Vue dom elements ([#1610](https://github.com/tailwindlabs/headlessui/pull/1610))
 - Ensure `CMD`+`Backspace` works in nullable mode for `Combobox` component ([#1617](https://github.com/tailwindlabs/headlessui/pull/1617))
 - Properly merge incoming props with own props ([#1651](https://github.com/tailwindlabs/headlessui/pull/1651))
+- Ensure `PopoverPanel` can be used inside `<transition>` ([#1653](https://github.com/tailwindlabs/headlessui/pull/1653))
 
 ## [1.6.5] - 2022-06-20
 

packages/@headlessui-vue/src/components/popover/popover.ts

@@ -542,7 +542,7 @@ export let PopoverPanel = defineComponent({
       function run() {
         match(direction.value, {
           [TabDirection.Forwards]: () => {
-            focusIn(el, Focus.First)
+            focusIn(el, Focus.Next)
           },
           [TabDirection.Backwards]: () => {
             // Coming from the Popover.Panel (which is portalled to somewhere else). Let's redirect
@@ -592,7 +592,7 @@ export let PopoverPanel = defineComponent({
 
             focusIn(combined, Focus.First, false)
           },
-          [TabDirection.Backwards]: () => focusIn(el, Focus.Last),
+          [TabDirection.Backwards]: () => focusIn(el, Focus.Previous),
         })
       }
 
@@ -618,38 +618,43 @@ export let PopoverPanel = defineComponent({
         tabIndex: -1,
       }
 
-      return h(Fragment, [
-        visible.value &&
-          api.isPortalled.value &&
-          h(Hidden, {
-            id: beforePanelSentinelId,
-            ref: api.beforePanelSentinel,
-            features: HiddenFeatures.Focusable,
-            as: 'button',
-            type: 'button',
-            onFocus: handleBeforeFocus,
-          }),
-        render({
-          ourProps,
-          theirProps: { ...attrs, ...props },
-          slot,
-          attrs,
-          slots,
-          features: Features.RenderStrategy | Features.Static,
-          visible: visible.value,
-          name: 'PopoverPanel',
-        }),
-        visible.value &&
-          api.isPortalled.value &&
-          h(Hidden, {
-            id: afterPanelSentinelId,
-            ref: api.afterPanelSentinel,
-            features: HiddenFeatures.Focusable,
-            as: 'button',
-            type: 'button',
-            onFocus: handleAfterFocus,
-          }),
-      ])
+      return render({
+        ourProps,
+        theirProps: { ...attrs, ...props },
+        attrs,
+        slot,
+        slots: {
+          ...slots,
+          default: (...args) => [
+            h(Fragment, [
+              visible.value &&
+                api.isPortalled.value &&
+                h(Hidden, {
+                  id: beforePanelSentinelId,
+                  ref: api.beforePanelSentinel,
+                  features: HiddenFeatures.Focusable,
+                  as: 'button',
+                  type: 'button',
+                  onFocus: handleBeforeFocus,
+                }),
+              slots.default?.(...args),
+              visible.value &&
+                api.isPortalled.value &&
+                h(Hidden, {
+                  id: afterPanelSentinelId,
+                  ref: api.afterPanelSentinel,
+                  features: HiddenFeatures.Focusable,
+                  as: 'button',
+                  type: 'button',
+                  onFocus: handleAfterFocus,
+                }),
+            ]),
+          ],
+        },
+        features: Features.RenderStrategy | Features.Static,
+        visible: visible.value,
+        name: 'PopoverPanel',
+      })
     }
   },
 })

packages/@headlessui-vue/src/internal/focus-sentinel.ts

@@ -33,7 +33,7 @@ export let FocusSentinel = defineComponent({
 
             // Try to move focus to the correct element. This depends on the implementation
             // of `onFocus` of course since it would be different for each place we use it in.
-            if (props.onFocus()) {
+            if (props.onFocus?.()) {
               enabled.value = false
               cancelAnimationFrame(frame)
               return

packages/@headlessui-vue/src/test-utils/interactions.ts

@@ -232,7 +232,7 @@ export async function click(
 ) {
   try {
     if (element === null) return expect(element).not.toBe(null)
-    if (element.disabled) return
+    if (element instanceof HTMLButtonElement && element.disabled) return
 
     let options = { button }