Scrollbar for the Select component with more than 6 items on iPad not appearing until touch

[zijianhuang]

Bug:

In iPad, the Material2 Select component with more than 6 options does not display a vertical scrollbar when dropping down, so the user would not know there are more options through a snapshot until touching the list. However, if the user touch-selects an option, the scrollbar will hardly be noticeable. This is bad for the affordance of the dropdown list.

What is the expected behavior?

In iPad, HTML Select+Option with many options will display a vertical scrollbar for around 1 second when dropping down, so the user would know there are more options through a snapshot, without touching the list.

In Android, the Material2 Select component with many options does display a vertical scrollbar for around 1 second when dropping down, so the user would know there are more options through a snapshot.

In iPad, the Select component should have similar behavior for affordance .

What are the steps to reproduce?

In https://material.angular.io/components/select/overview, pick any example and add more options, you will see.

What is the use-case or motivation for changing an existing behavior?

1. Affordance for telling the user more options available.
2. Being consist with the behavior on Android, and HTML Select+Option on iPad

Which versions of Angular, Material, OS, TypeScript, browsers are affected?

Angular 5, Material 5.0.0-rc0. All latest browsers. iPad 3 iOS 9.3; iPad Pro iOS 10.3.

[mmxcrono]

I agree, there are concerns for this in forms as the user is not aware of all options that are available unless they touch and see the scrollbar afterwards.