4 files changed, 20 insertions, 9 deletions

diff --git a/app/javascript/mastodon/components/column.js b/app/javascript/mastodon/components/column.js
index 93f1d6260..05a7c1436 100644
--- a/app/javascript/mastodon/components/column.js
+++ b/app/javascript/mastodon/components/column.js
@@ -1,7 +1,7 @@
 import React from 'react';
 import PropTypes from 'prop-types';
 import detectPassiveEvents from 'detect-passive-events';
-import scrollTop from '../scroll';
+import { scrollTop } from '../scroll';
 
 export default class Column extends React.PureComponent {
 
diff --git a/app/javascript/mastodon/features/ui/components/column.js b/app/javascript/mastodon/features/ui/components/column.js
index aea102aac..9031c16fc 100644
--- a/app/javascript/mastodon/features/ui/components/column.js
+++ b/app/javascript/mastodon/features/ui/components/column.js
@@ -2,7 +2,7 @@ import React from 'react';
 import ColumnHeader from './column_header';
 import PropTypes from 'prop-types';
 import { debounce } from 'lodash';
-import scrollTop from '../../../scroll';
+import { scrollTop } from '../../../scroll';
 import { isMobile } from '../../../is_mobile';
 
 export default class Column extends React.PureComponent {
diff --git a/app/javascript/mastodon/features/ui/components/columns_area.js b/app/javascript/mastodon/features/ui/components/columns_area.js
index 63bd1b021..7652d67a0 100644
--- a/app/javascript/mastodon/features/ui/components/columns_area.js
+++ b/app/javascript/mastodon/features/ui/components/columns_area.js
@@ -12,6 +12,8 @@ import ColumnLoading from './column_loading';
 import BundleColumnError from './bundle_column_error';
 import { Compose, Notifications, HomeTimeline, CommunityTimeline, PublicTimeline, HashtagTimeline, FavouritedStatuses } from '../../ui/util/async-components';
 
+import { scrollRight } from '../../../scroll';
+
 const componentMap = {
   'COMPOSE': Compose,
   'HOME': HomeTimeline,
@@ -49,9 +51,13 @@ export default class ColumnsArea extends ImmutablePureComponent {
     this.setState({ shouldAnimate: true });
   }
 
-  componentDidUpdate() {
+  componentDidUpdate(prevProps) {
     this.lastIndex = getIndex(this.context.router.history.location.pathname);
     this.setState({ shouldAnimate: true });
+
+    if (this.props.children !== prevProps.children) {
+      scrollRight(this.node);
+    }
   }
 
   handleSwipe = (index) => {
@@ -74,6 +80,10 @@ export default class ColumnsArea extends ImmutablePureComponent {
     }
   }
 
+  setRef = (node) => {
+    this.node = node;
+  }
+
   renderView = (link, index) => {
     const columnIndex = getIndex(this.context.router.history.location.pathname);
     const title = this.props.intl.formatMessage({ id: link.props['data-preview-title-id'] });
@@ -114,7 +124,7 @@ export default class ColumnsArea extends ImmutablePureComponent {
     }
 
     return (
-      <div className='columns-area'>
+      <div className='columns-area' ref={this.setRef}>
         {columns.map(column => {
           const params = column.get('params', null) === null ? null : column.get('params').toJS();
 
diff --git a/app/javascript/mastodon/scroll.js b/app/javascript/mastodon/scroll.js
index c089d37db..44f95b17f 100644
--- a/app/javascript/mastodon/scroll.js
+++ b/app/javascript/mastodon/scroll.js
@@ -1,9 +1,9 @@
 const easingOutQuint = (x, t, b, c, d) => c * ((t = t / d - 1) * t * t * t * t + 1) + b;
 
-const scrollTop = (node) => {
+const scroll = (node, key, target) => {
   const startTime = Date.now();
-  const offset    = node.scrollTop;
-  const targetY   = -offset;
+  const offset    = node[key];
+  const gap       = target - offset;
   const duration  = 1000;
   let interrupt   = false;
 
@@ -15,7 +15,7 @@ const scrollTop = (node) => {
       return;
     }
 
-    node.scrollTop = easingOutQuint(0, elapsed, offset, targetY, duration);
+    node[key] = easingOutQuint(0, elapsed, offset, gap, duration);
     requestAnimationFrame(step);
   };
 
@@ -26,4 +26,5 @@ const scrollTop = (node) => {
   };
 };
 
-export default scrollTop;
+export const scrollRight = (node) => scroll(node, 'scrollLeft', node.scrollWidth);
+export const scrollTop = (node) => scroll(node, 'scrollTop', 0);