Autocomplete dropdown closes if scrollbar is dragged on IE11

[cnotv]

Reproduction link

https://stackblitz.com/edit/angular-hzqs6m?file=src/app/app.component.ts

Steps to reproduce

• Click in the input field to display the dropdown (focus)
• Try to drag the scrolling bar
• The dropdown closes instead of allowing us to scroll

What is expected?

It is possible to scroll.

What is actually happening?

The dropdown closes.

Environment	Info
ng-zorro-antd	8.4.0
Browser	IE11

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It does not happen to the other dropdowns, e.g. Select inputs.
I guess must be changed the closing event to the single option, rather than the whole dropdown.

[cnotv]

I've been forced to create a directive with the same selector which on keydown/focus add a listener to prevent the blur of the element and on blur to remove it.
However has not been possible to solve it using the ElementRef, nor using the querySelector.
Instead I'd to brutally hack it with

window.addEventListener('blur', preventAll, true)

where preventAll is a function which ... prevents all :)

I will consider to create a PR.