### Why does the warning `findDOMNode is deprecated` sometimes appear in strict mode? This is due to the implementation of `rc-trigger`. `rc-trigger` forces children to accept ref, otherwise it will fall back to findDOMNode, so children need to be native html tags. If not, you need to use `React.forwardRef` transparently passes `ref` to native html tags. - `findDOMNode is deprecated` reproduce: - Using `forwardRef` to fix: ### Why is the tooltip for my custom component not opening? Similar issues: [#15909](https://github.com/ant-design/ant-design/issues/15909), [#12812](https://github.com/ant-design/ant-design/issues/12812). Please ensure that the child node to accept `onMouseEnter`, `onMouseLeave`, `onPointerEnter`, `onPointerLeave`, `onFocus`, and `onClick` events, If you create your own component and do not explicitly add these mouse and pointer events as props, the tooltip will never appear. [See Example](http://ant.design/components/tooltip#tooltip-demo-wrap-custom-component). ### What's the placement logic? It will follow `placement` config when screen has enough space. And flip when space is not enough (Such as `top` to `bottom` or `topLeft` to `bottomLeft`). Single direction such as `top` `bottom` `left` `right` will auto shift on the view: When `placement` is set to edge align such as `topLeft` `bottomRight`, it will only do flip but not do shift.