Updating combobox docs to explain onOpenChange changes

packages/@react-spectrum/combobox/docs/ComboBox.mdx

@@ -592,7 +592,7 @@ function Example() {
       label="To:"
       validationState={isValid ? 'valid' : 'invalid'}
       defaultItems={options}
-      value={value}
+      inputValue={value}
       onInputChange={setValue}
       placeholder="Enter recipient email"
       allowsCustomValue>
@@ -607,7 +607,9 @@ By default, ComboBox uses a string "contains" filtering strategy when deciding w
 by filtering the list of items yourself and passing the filtered list to the ComboBox via the `items` prop.
 
 The example below uses a string "startsWith" filter function obtained from the `useFilter` hook to display items that start with the ComboBox's current input
-value only.
+value only. By using the `menuTrigger` returned by `onOpenChange`, it also handles displaying the entire option list regardless of the current filter value when the ComboBox menu is
+opened via the trigger button or arrow keys. `menuTrigger` tells you if the menu was opened manually by the user ("manual"), by focusing the ComboBox ("focus"), or by
+changes in the input field ("input"), allowing you to make updates to other controlled aspects of your ComboBox accordingly.
 
 ```tsx example
 function Example() {
@@ -623,17 +625,28 @@ function Example() {
     {id: 9, email: 'subscribe@email.com'}
   ];
 
-  let {startsWith} = useFilter({sensitivity: 'base'});
+  let [showAll, setShowAll] = React.useState(false);
   let [filterValue, setFilterValue] = React.useState('');
+  let {startsWith} = useFilter({sensitivity: 'base'});
   let filteredItems = React.useMemo(() => options.filter(item => startsWith(item.email, filterValue)), [options, filterValue]);
 
   return (
     <ComboBox
+      onOpenChange={(isOpen, menuTrigger) => {
+        // Show all items if menu is opened manually
+        // i.e. by the arrow keys or trigger button
+        if (menuTrigger === 'manual' && isOpen) {
+          setShowAll(true);
+        }
+      }}
       width="size-3000"
       label="To:"
-      items={filteredItems}
-      value={filterValue}
-      onInputChange={setFilterValue}
+      items={showAll ? options : filteredItems}
+      inputValue={filterValue}
+      onInputChange={(value) => {
+        setShowAll(false);
+        setFilterValue(value);
+      }}
       placeholder="Enter recipient email"
       allowsCustomValue>
       {item => <Item>{item.email}</Item>}