Add caption for empty TAC

res/css/structures/_ThreadsActivityCentre.pcss

@@ -66,3 +66,9 @@
         }
     }
 }
+
+.mx_ThreadsActivityCentre_emptyCaption {
+    padding-left: 16px;
+    padding-right: 16px;
+    font-size: 13px;
+}

src/components/views/spaces/threads-activity-centre/ThreadsActivityCentre.tsx

@@ -77,6 +77,11 @@ export function ThreadsActivityCentre({ displayButtonLabel }: ThreadsActivityCen
                         onClick={() => setOpen(false)}
                     />
                 ))}
+                {roomsAndNotifications.rooms.length === 0 && (
+                    <div className="mx_ThreadsActivityCentre_emptyCaption">
+                        {_t("tac|no_rooms_with_unreads_threads")}
+                    </div>
+                )}
             </div>
         </Menu>
     );

src/i18n/strings/en_EN.json

@@ -3120,6 +3120,9 @@
         "empty": "You don't currently have any stickerpacks enabled",
         "empty_add_prompt": "Add some now"
     },
+    "tac": {
+        "no_rooms_with_unreads_threads": "You don't have rooms with unread threads yet."
+    },
     "terms": {
         "column_document": "Document",
         "column_service": "Service",