popconfirm控件问题

[nlx0201]

• I have searched the issues of this repository and believe that this is not a duplicate.

Reproduction link

Steps to reproduce

1. 设置父div高度为40，布局为flex column，设定overflow-y为auto。
2. 内部放置3个高度为30的按钮，包含popconfirm。
3. 点击button控件，弹出popconfirm, 滚动滚动条，popconfirm不会跟随内部按钮滚动。

What is expected?

期望popconfirm跟随button滚动

What is actually happening?

无法跟随滚动，popconfirm固定不变

Environment	Info
antd	3.17.0
React	15.4.2
System	window 10
Browser	chrome

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能否补充popuptriggercontainer属性

[afc163]

Please read FAQ before openning new issue.

https://ant.design/docs/react/faq-cn

#3487 #3438

[nlx0201]

看到了，麻烦API说明文档上补充此属性

[afc163]

因为 Popover 和 Popconfirm 都是基于 Tooltip 实现的，所有都链到这里了。