Show room preview bar with maximised widgets

res/css/views/right_panel/_TimelineCard.scss

@@ -123,4 +123,5 @@ limitations under the License.
 .mx_TimelineCard_timeline {
     overflow: hidden;
     position: relative; // offset parent for jump to bottom button
+    flex: 1;
 }

src/components/structures/RoomView.tsx

@@ -2126,12 +2126,15 @@ export class RoomView extends React.Component<IRoomProps, IRoomState> {
                 </>;
                 break;
             case MainSplitContentType.MaximisedWidget:
-                mainSplitBody = <AppsDrawer
-                    room={this.state.room}
-                    userId={this.context.credentials.userId}
-                    resizeNotifier={this.props.resizeNotifier}
-                    showApps={true}
-                />;
+                mainSplitBody = <>
+                    <AppsDrawer
+                        room={this.state.room}
+                        userId={this.context.credentials.userId}
+                        resizeNotifier={this.props.resizeNotifier}
+                        showApps={true}
+                    />
+                    { previewBar }
+                </>;
                 break;
             case MainSplitContentType.Video: {
                 const app = getVoiceChannel(this.state.room.roomId);

src/components/views/right_panel/TimelineCard.tsx

@@ -221,6 +221,9 @@ export default class TimelineCard extends React.Component<IProps, IState> {
 
         const isUploading = ContentMessages.sharedInstance().getCurrentUploads(this.props.composerRelation).length > 0;
 
+        const myMembership = this.props.room.getMyMembership();
+        const canSpeak = myMembership === "join";
+
         return (
             <RoomContext.Provider value={{
                 ...this.context,
@@ -270,15 +273,17 @@ export default class TimelineCard extends React.Component<IProps, IState> {
                         <UploadBar room={this.props.room} relation={this.props.composerRelation} />
                     ) }
 
-                    <MessageComposer
-                        room={this.props.room}
-                        relation={this.props.composerRelation}
-                        resizeNotifier={this.props.resizeNotifier}
-                        replyToEvent={this.state.replyToEvent}
-                        permalinkCreator={this.props.permalinkCreator}
-                        e2eStatus={this.props.e2eStatus}
-                        compact={true}
-                    />
+                    { canSpeak && (
+                        <MessageComposer
+                            room={this.props.room}
+                            relation={this.props.composerRelation}
+                            resizeNotifier={this.props.resizeNotifier}
+                            replyToEvent={this.state.replyToEvent}
+                            permalinkCreator={this.props.permalinkCreator}
+                            e2eStatus={this.props.e2eStatus}
+                            compact={true}
+                        />
+                    ) }
                 </BaseCard>
             </RoomContext.Provider>
         );