fix(InputMenu): emit focus event (#2386)

Co-authored-by: Benjamin Canac <canacb1@gmail.com>

docs/app/components/content/examples/input-menu/InputMenuOpenFocusExample.vue

@@ -0,0 +1,14 @@
+<script setup lang="ts">
+const open = ref(false)
+const items = ref(['Backlog', 'Todo', 'In Progress', 'Done'])
+const selected = ref('Backlog')
+</script>
+
+<template>
+  <UInputMenu
+    v-model="selected"
+    v-model:open="open"
+    :items="items"
+    @focus="open = true"
+  />
+</template>

docs/content/3.components/input-menu.md

@@ -611,6 +611,16 @@ name: 'input-menu-open-example'
 In this example, press :kbd{value="O"} to toggle the InputMenu.
 ::
 
+### Control open state on focus
+
+You can also use the `@focus` directive to control the open state.
+
+::component-example
+---
+name: 'input-menu-open-focus-example'
+---
+::
+
 ### Control search term
 
 Use the `v-model:search-term` directive to control the search term.