## Description
This PR fixes DropdownMenu arrow icon position when
`InputDecoration.isCollapsed` is set to true and
`InputDecoration.suffixConstraints` is set to a smaller value than the
min interactive height.
It makes it possible to use collapsed `DropdownMenu` such as:
_____
Before this PR and https://github.com/flutter/flutter/pull/153089,
`InputDecoration.isCollapsed` had no impact on the `DropdownMenu` height
and there was no solution to reduce the height because its minimum
height is enforced by the `IconButton` (arrow down or up) which is part
of the `DropdownMenu`.
Since https://github.com/flutter/flutter/pull/153089, the height can be
reduce with `InputDecoration.suffixIconConstraints` but it results in
the icon being misaligned:
After this PR:
When `InputDecoration.suffixIconConstraints` is used the icon is
correctly aligned:
<details><summary>Code sample</summary>
```dart
import 'package:flutter/material.dart';
void main() {
runApp(const MyApp());
}
class MyApp extends StatelessWidget {
const MyApp({super.key});
@override
Widget build(BuildContext context) {
return const MaterialApp(
title: 'Flutter Demo',
home: MyHomePage(title: 'Flutter Demo Home Page'),
);
}
}
class MyHomePage extends StatefulWidget {
const MyHomePage({super.key, required this.title});
final String title;
@override
State<MyHomePage> createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
@override
Widget build(BuildContext context) {
return const Scaffold(
body: Center(
child: Center(
child: DropdownMenu<String>(
dropdownMenuEntries: [
DropdownMenuEntry(label: 'Item 1', value: '1'),
DropdownMenuEntry(label: 'Item 2', value: '2'),
],
inputDecorationTheme: InputDecorationTheme(
contentPadding: EdgeInsets.fromLTRB(5, 0, 5, 0),
isCollapsed: true,
// Usable since https://github.com/flutter/flutter/pull/153089.
suffixIconConstraints: BoxConstraints(minHeight: 24, maxHeight: 24),
filled: true,
),
),
),
),
);
}
}
```
</details>
## Related Issue
Fixes [DropdownMenu inputDecoration isCollapsed property does not reduce
vertical spacing](https://github.com/flutter/flutter/issues/138691)
## Tests
Adds 2 tests.
44ff2f5977