add doublick handler for MarkdownPreview to turn off preview mode

browser/components/MarkdownPreview.js

@@ -44,18 +44,23 @@ export default class MarkdownPreview extends React.Component {
     }
   }
 
+  handleDoubleClick (e) {
+    this.props.onDoubleClick(e)
+  }
+
   render () {
     let isEmpty = this.props.content.trim().length === 0
     let content = isEmpty
       ? '(Empty content)'
       : this.props.content
     return (
-      <div className={'MarkdownPreview' + (this.props.className != null ? ' ' + this.props.className : '') + (isEmpty ? ' empty' : '')} dangerouslySetInnerHTML={{__html: ' ' + markdown(content)}}/>
+      <div onDoubleClick={e => this.handleDoubleClick(e)} className={'MarkdownPreview' + (this.props.className != null ? ' ' + this.props.className : '') + (isEmpty ? ' empty' : '')} dangerouslySetInnerHTML={{__html: ' ' + markdown(content)}}/>
     )
   }
 }
 
 MarkdownPreview.propTypes = {
+  onDoubleClick: PropTypes.func,
   className: PropTypes.string,
   content: PropTypes.string
 }

browser/main/HomePage/ArticleDetail/index.js

@@ -264,6 +264,12 @@ export default class ArticleDetail extends React.Component {
     }
   }
 
+  handlePreviewButtonDoubleClick (e) {
+    this.setState({
+      previewMode: false
+    })
+  }
+
   render () {
     let { folders, status, tags, activeArticle, modified, user } = this.props
     if (activeArticle == null) return this.renderEmpty()
@@ -354,7 +360,7 @@ export default class ArticleDetail extends React.Component {
           {status.isTutorialOpen ? modeSelectTutorialElement : null}
 
           {this.state.previewMode
-            ? <MarkdownPreview ref='preview' content={this.state.article.content}/>
+            ? <MarkdownPreview ref='preview' onDoubleClick={e => this.handlePreviewButtonDoubleClick(e)} content={this.state.article.content}/>
             : (<CodeEditor
                 ref='code'
                 onChange={(e, value) => this.handleContentChange(e, value)}