Add hints about incomplete remote content to web UI (#14031)

app/javascript/mastodon/components/scrollable_list.js

@@ -32,6 +32,7 @@ export default class ScrollableList extends PureComponent {
     hasMore: PropTypes.bool,
     numPending: PropTypes.number,
     prepend: PropTypes.node,
+    append: PropTypes.node,
     alwaysPrepend: PropTypes.bool,
     emptyMessage: PropTypes.node,
     children: PropTypes.node,
@@ -280,7 +281,7 @@ export default class ScrollableList extends PureComponent {
   }
 
   render () {
-    const { children, scrollKey, trackScroll, shouldUpdateScroll, showLoading, isLoading, hasMore, numPending, prepend, alwaysPrepend, emptyMessage, onLoadMore } = this.props;
+    const { children, scrollKey, trackScroll, shouldUpdateScroll, showLoading, isLoading, hasMore, numPending, prepend, alwaysPrepend, append, emptyMessage, onLoadMore } = this.props;
     const { fullscreen } = this.state;
     const childrenCount = React.Children.count(children);
 
@@ -327,6 +328,8 @@ export default class ScrollableList extends PureComponent {
             ))}
 
             {loadMore}
+
+            {!hasMore && append}
           </div>
         </div>
       );

app/javascript/mastodon/components/timeline_hint.js

@@ -0,0 +1,18 @@
+import React from 'react';
+import PropTypes from 'prop-types';
+import { FormattedMessage } from 'react-intl';
+
+const TimelineHint = ({ resource, url }) => (
+  <div className='timeline-hint'>
+    <strong><FormattedMessage id='timeline_hint.remote_resource_not_displayed' defaultMessage='{resource} from other servers are not displayed.' values={{ resource }} /></strong>
+    <br />
+    <a href={url} target='_blank'><FormattedMessage id='account.browse_more_on_origin_server' defaultMessage='Browse more on the original profile' /></a>
+  </div>
+);
+
+TimelineHint.propTypes = {
+  resource: PropTypes.node.isRequired,
+  url: PropTypes.string.isRequired,
+};
+
+export default TimelineHint;