fix(VCombobox): re-compute menu items before setting index (#13825)

fixes #12567

Author: KaelWD

Diff for: packages/vuetify/src/components/VSelect/VSelect.ts

@@ -658,12 +658,6 @@ export default baseMixins.extend<options>().extend({
       const keyCode = e.keyCode
       const menu = this.$refs.menu
 
-      // If enter, space, open menu
-      if ([
-        keyCodes.enter,
-        keyCodes.space,
-      ].includes(keyCode)) this.activateMenu()
-
       this.$emit('keydown', e)
 
       if (!menu) return
@@ -677,6 +671,12 @@ export default baseMixins.extend<options>().extend({
         })
       }
 
+      // If enter, space, open menu
+      if ([
+        keyCodes.enter,
+        keyCodes.space,
+      ].includes(keyCode)) this.activateMenu()
+
       // If menu is not active, up/down/home/end can do
       // one of 2 things. If multiple, opens the
       // menu, if not, will cycle through all
@@ -709,6 +709,7 @@ export default baseMixins.extend<options>().extend({
       if (!menu || !this.isDirty) return
 
       // When menu opens, set index of first active item
+      this.$refs.menu.getTiles()
       for (let i = 0; i < menu.tiles.length; i++) {
         if (menu.tiles[i].getAttribute('aria-selected') === 'true') {
           this.setMenuIndex(i)
@@ -839,11 +840,6 @@ export default baseMixins.extend<options>().extend({
             (this.$refs.menu as { [key: string]: any }).updateDimensions()
         })
 
-        // We only need to reset list index for multiple
-        // to keep highlight when an item is toggled
-        // on and off
-        if (!this.multiple) return
-
         const listIndex = this.getMenuIndex()
 
         this.setMenuIndex(-1)