fix: corret the dragpreview example by adding an effect dependency

packages/examples/src/02 Drag Around/Custom Drag Layer/Box.tsx

@@ -1,4 +1,4 @@
-import React, { memo } from 'react'
+import React from 'react'
 
 const styles: React.CSSProperties = {
 	border: '1px dashed gray',
@@ -11,9 +11,9 @@ export interface BoxProps {
 	yellow?: boolean
 }
 
-const Box: React.FC<BoxProps> = memo(({ title, yellow }) => {
+const Box: React.FC<BoxProps> = ({ title, yellow }) => {
 	const backgroundColor = yellow ? 'yellow' : 'white'
 	return <div style={{ ...styles, backgroundColor }}>{title}</div>
-})
+}
 
 export default Box

packages/examples/src/02 Drag Around/Custom Drag Layer/BoxDragPreview.tsx

@@ -1,4 +1,4 @@
-import React, { useState, useEffect, memo } from 'react'
+import React, { useState, useEffect } from 'react'
 import Box from './Box'
 
 const styles = {
@@ -11,19 +11,24 @@ export interface BoxDragPreviewProps {
 	title: string
 }
 
-const BoxDragPreview: React.FC<BoxDragPreviewProps> = memo(({ title }) => {
+const BoxDragPreview: React.FC<BoxDragPreviewProps> = ({ title }) => {
 	const [tickTock, setTickTock] = useState(false)
 
-	useEffect(function subscribeToIntervalTick() {
-		const interval = setInterval(() => setTickTock(!tickTock), 500)
-		return () => clearInterval(interval)
-	}, [])
+	useEffect(
+		function subscribeToIntervalTick() {
+			const interval = setInterval(() => {
+				setTickTock(!tickTock)
+			}, 500)
+			return () => clearInterval(interval)
+		},
+		[tickTock],
+	)
 
 	return (
 		<div style={styles}>
 			<Box title={title} yellow={tickTock} />
 		</div>
 	)
-})
+}
 
 export default BoxDragPreview

packages/examples/src/02 Drag Around/Custom Drag Layer/CustomDragLayer.tsx

@@ -49,7 +49,7 @@ export interface CustomDragLayerProps {
 	snapToGrid: boolean
 }
 
-const CustomDragLayer: React.SFC<CustomDragLayerProps> = props => {
+const CustomDragLayer: React.FC<CustomDragLayerProps> = props => {
 	const { item, itemType, isDragging } = props
 
 	function renderItem() {