Add tooltip to close button

Author: gaearon

packages/react-error-overlay/src/components/close.js

@@ -2,9 +2,10 @@
 import { applyStyles } from '../utils/dom/css';
 import { hintsStyle, hintStyle, closeButtonStyle } from '../styles';
 
-function createHint(document: Document, hint: string) {
+function createHint(document: Document, hint: string, title: string) {
   const span = document.createElement('span');
   span.appendChild(document.createTextNode(hint));
+  span.setAttribute('title', title);
   applyStyles(span, hintStyle);
   return span;
 }
@@ -14,7 +15,7 @@ function createClose(document: Document, callback: CloseCallback) {
   const hints = document.createElement('div');
   applyStyles(hints, hintsStyle);
 
-  const close = createHint(document, '×');
+  const close = createHint(document, '×', 'Click or press Escape to dismiss.');
   close.addEventListener('click', () => callback());
   applyStyles(close, closeButtonStyle);
   hints.appendChild(close);