From d62d1d670b1f718010f9ef1af9b19fee820b088b Mon Sep 17 00:00:00 2001
From: David Nagle <nagledb@gmail.com>
Date: Fri, 26 Oct 2018 11:17:06 -0700
Subject: [PATCH] Added option to disable scroll sync.

---
 browser/components/MarkdownSplitEditor.js     |  2 ++
 browser/main/lib/ConfigManager.js             |  1 +
 browser/main/modals/PreferencesModal/UiTab.js | 11 +++++++++++
 3 files changed, 14 insertions(+)

diff --git a/browser/components/MarkdownSplitEditor.js b/browser/components/MarkdownSplitEditor.js
index 7d01e3b53..ca2d31087 100644
--- a/browser/components/MarkdownSplitEditor.js
+++ b/browser/components/MarkdownSplitEditor.js
@@ -30,6 +30,8 @@ class MarkdownSplitEditor extends React.Component {
   }
 
   handleScroll (e) {
+    if (!this.props.config.preview.scrollSync) return
+
     const previewDoc = _.get(this, 'refs.preview.refs.root.contentWindow.document')
     const codeDoc = _.get(this, 'refs.code.editor.doc')
     let srcTop, srcHeight, targetTop, targetHeight
diff --git a/browser/main/lib/ConfigManager.js b/browser/main/lib/ConfigManager.js
index 33cab7aac..021ea5cc7 100644
--- a/browser/main/lib/ConfigManager.js
+++ b/browser/main/lib/ConfigManager.js
@@ -62,6 +62,7 @@ export const DEFAULT_CONFIG = {
     latexBlockClose: '$$',
     plantUMLServerAddress: 'http://www.plantuml.com/plantuml',
     scrollPastEnd: false,
+    scrollSync: true,
     smartQuotes: true,
     breaks: true,
     smartArrows: false,
diff --git a/browser/main/modals/PreferencesModal/UiTab.js b/browser/main/modals/PreferencesModal/UiTab.js
index 638fab90b..6a9abe656 100644
--- a/browser/main/modals/PreferencesModal/UiTab.js
+++ b/browser/main/modals/PreferencesModal/UiTab.js
@@ -104,6 +104,7 @@ class UiTab extends React.Component {
         latexBlockClose: this.refs.previewLatexBlockClose.value,
         plantUMLServerAddress: this.refs.previewPlantUMLServerAddress.value,
         scrollPastEnd: this.refs.previewScrollPastEnd.checked,
+        scrollSync: this.refs.previewScrollSync.checked,
         smartQuotes: this.refs.previewSmartQuotes.checked,
         breaks: this.refs.previewBreaks.checked,
         smartArrows: this.refs.previewSmartArrows.checked,
@@ -561,6 +562,16 @@ class UiTab extends React.Component {
               {i18n.__('Allow preview to scroll past the last line')}
             </label>
           </div>
+          <div styleName='group-checkBoxSection'>
+            <label>
+              <input onChange={(e) => this.handleUIChange(e)}
+                checked={this.state.config.preview.scrollSync}
+                ref='previewScrollSync'
+                type='checkbox'
+              />&nbsp;
+              {i18n.__('When scrolling, synchronize preview with editor')}
+            </label>
+          </div>
           <div styleName='group-checkBoxSection'>
             <label>
               <input onChange={(e) => this.handleUIChange(e)}