Freeze scroll position when a dropdown menu is open in the TL (#14271)

* Freeze scroll position when a dropdown menu is open in the TL

* Apply this to direct TL as well

* Fix case when mouse leaves the menu

app/javascript/mastodon/components/scrollable_list.js

@@ -10,10 +10,18 @@ import { List as ImmutableList } from 'immutable';
 import classNames from 'classnames';
 import { attachFullscreenListener, detachFullscreenListener, isFullscreen } from '../features/ui/util/fullscreen';
 import LoadingIndicator from './loading_indicator';
+import { connect } from 'react-redux';
 
 const MOUSE_IDLE_DELAY = 300;
 
-export default class ScrollableList extends PureComponent {
+const mapStateToProps = (state, { scrollKey }) => {
+  return {
+    preventScroll: scrollKey === state.getIn(['dropdown_menu', 'scroll_key']),
+  };
+};
+
+export default @connect(mapStateToProps)
+class ScrollableList extends PureComponent {
 
   static contextTypes = {
     router: PropTypes.object,
@@ -37,6 +45,7 @@ export default class ScrollableList extends PureComponent {
     emptyMessage: PropTypes.node,
     children: PropTypes.node,
     bindToDocument: PropTypes.bool,
+    preventScroll: PropTypes.bool,
   };
 
   static defaultProps = {
@@ -129,7 +138,7 @@ export default class ScrollableList extends PureComponent {
   });
 
   handleMouseIdle = () => {
-    if (this.scrollToTopOnMouseIdle) {
+    if (this.scrollToTopOnMouseIdle && !this.props.preventScroll) {
       this.setScrollTop(0);
     }
 
@@ -179,7 +188,7 @@ export default class ScrollableList extends PureComponent {
       this.getFirstChildKey(prevProps) !== this.getFirstChildKey(this.props);
     const pendingChanged = (prevProps.numPending > 0) !== (this.props.numPending > 0);
 
-    if (pendingChanged || someItemInserted && (this.getScrollTop() > 0 || this.mouseMovedRecently)) {
+    if (pendingChanged || someItemInserted && (this.getScrollTop() > 0 || this.mouseMovedRecently || this.props.preventScroll)) {
       return this.getScrollHeight() - this.getScrollTop();
     } else {
       return null;

app/javascript/mastodon/components/status.js

@@ -94,6 +94,7 @@ class Status extends ImmutablePureComponent {
     updateScrollBottom: PropTypes.func,
     cacheMediaWidth: PropTypes.func,
     cachedMediaWidth: PropTypes.number,
+    scrollKey: PropTypes.string,
   };
 
   // Avoid checking props that are functions (and whose equality will always
@@ -264,7 +265,7 @@ class Status extends ImmutablePureComponent {
     let media = null;
     let statusAvatar, prepend, rebloggedByText;
 
-    const { intl, hidden, featured, otherAccounts, unread, showThread } = this.props;
+    const { intl, hidden, featured, otherAccounts, unread, showThread, scrollKey } = this.props;
 
     let { status, account, ...other } = this.props;
 
@@ -459,7 +460,7 @@ class Status extends ImmutablePureComponent {
 
             {media}
 
-            <StatusActionBar status={status} account={account} {...other} />
+            <StatusActionBar scrollKey={scrollKey} status={status} account={account} {...other} />
           </div>
         </div>
       </HotKeys>

app/javascript/mastodon/components/status_action_bar.js

@@ -85,6 +85,7 @@ class StatusActionBar extends ImmutablePureComponent {
     onPin: PropTypes.func,
     onBookmark: PropTypes.func,
     withDismiss: PropTypes.bool,
+    scrollKey: PropTypes.string,
     intl: PropTypes.object.isRequired,
   };
 
@@ -229,7 +230,7 @@ class StatusActionBar extends ImmutablePureComponent {
   }
 
   render () {
-    const { status, relationship, intl, withDismiss } = this.props;
+    const { status, relationship, intl, withDismiss, scrollKey } = this.props;
 
     const mutingConversation = status.get('muted');
     const anonymousAccess    = !me;
@@ -333,7 +334,16 @@ class StatusActionBar extends ImmutablePureComponent {
         {shareButton}
 
         <div className='status__action-bar-dropdown'>
-          <DropdownMenuContainer disabled={anonymousAccess} status={status} items={menu} icon='ellipsis-h' size={18} direction='right' title={intl.formatMessage(messages.more)} />
+          <DropdownMenuContainer
+            scrollKey={scrollKey}
+            disabled={anonymousAccess}
+            status={status}
+            items={menu}
+            icon='ellipsis-h'
+            size={18}
+            direction='right'
+            title={intl.formatMessage(messages.more)}
+          />
         </div>
       </div>
     );

app/javascript/mastodon/components/status_list.js

@@ -99,6 +99,7 @@ export default class StatusList extends ImmutablePureComponent {
           onMoveUp={this.handleMoveUp}
           onMoveDown={this.handleMoveDown}
           contextType={timelineId}
+          scrollKey={this.props.scrollKey}
           showThread
         />
       ))