Fix thread navigation in timeline (#12412)

* Remove thread dispatch action

* Add comment

* Add e2e test

playwright/e2e/threads/threads.spec.ts

@@ -447,4 +447,72 @@ test.describe("Threads", () => {
         await expect(locator.locator(".mx_EventTile").first().getByText("Hello Mr. Bot")).toBeAttached();
         await expect(locator.locator(".mx_EventTile").last().getByText("Hello Mr. User")).toBeAttached();
     });
+
+    test("navigate through right panel", async ({ page, app, user }) => {
+        // Create room
+        const roomId = await app.client.createRoom({});
+        await page.goto("/#/room/" + roomId);
+
+        /**
+         * Send a message in the main timeline
+         * @param message
+         */
+        const sendMessage = async (message: string) => {
+            const messageComposer = page.getByRole("region", { name: "Message composer" });
+            const textbox = messageComposer.getByRole("textbox", { name: "Send a message…" });
+            await textbox.fill(message);
+            await textbox.press("Enter");
+        };
+
+        /**
+         * Create a thread from the rootMessage and send a message in the thread
+         * @param rootMessage
+         * @param threadMessage
+         */
+        const createThread = async (rootMessage: string, threadMessage: string) => {
+            // First create a thread
+            const roomViewBody = page.locator(".mx_RoomView_body");
+            const messageTile = roomViewBody
+                .locator(".mx_EventTile[data-scroll-tokens]")
+                .filter({ hasText: rootMessage });
+            await messageTile.hover();
+            await messageTile.getByRole("button", { name: "Reply in thread" }).click();
+            await expect(page.locator(".mx_ThreadView_timelinePanelWrapper")).toHaveCount(1);
+
+            // Send a message in the thread
+            const threadPanel = page.locator(".mx_ThreadPanel");
+            const textbox = threadPanel.getByRole("textbox", { name: "Send a message…" });
+            await textbox.fill(threadMessage);
+            await textbox.press("Enter");
+            await expect(threadPanel.locator(".mx_EventTile_last").getByText(threadMessage)).toBeVisible();
+            // Close thread
+            await threadPanel.getByRole("button", { name: "Close" }).click();
+        };
+
+        await sendMessage("Hello Mr. Bot");
+        await sendMessage("Hello again Mr. Bot");
+        await createThread("Hello Mr. Bot", "Hello Mr. User in a thread");
+        await createThread("Hello again Mr. Bot", "Hello again Mr. User in a thread");
+
+        // Open thread panel
+        await page.getByRole("button", { name: "Threads" }).click();
+        const threadPanel = page.locator(".mx_ThreadPanel");
+        await expect(
+            threadPanel.locator(".mx_EventTile_last").getByText("Hello again Mr. User in a thread"),
+        ).toBeVisible();
+
+        // Open threads list
+        await threadPanel.getByRole("button", { name: "Threads" }).click();
+        const rightPanel = page.locator(".mx_RightPanel");
+        // Check that the threads are listed
+        await expect(rightPanel.locator(".mx_EventTile").getByText("Hello Mr. User in a thread")).toBeVisible();
+        await expect(rightPanel.locator(".mx_EventTile").getByText("Hello again Mr. User in a thread")).toBeVisible();
+
+        // Open the first thread
+        await rightPanel.locator(".mx_EventTile").getByText("Hello Mr. User in a thread").click();
+        await expect(rightPanel.locator(".mx_EventTile").getByText("Hello Mr. User in a thread")).toBeVisible();
+        await expect(
+            rightPanel.locator(".mx_EventTile").getByText("Hello again Mr. User in a thread"),
+        ).not.toBeVisible();
+    });
 });

src/components/structures/RoomView.tsx

@@ -707,6 +707,8 @@ export class RoomView extends React.Component<IRoomProps, IRoomState> {
             newState.initialEventPixelOffset = undefined;
 
             const thread = initialEvent?.getThread();
+            // Handle the use case of a link to a thread message
+            // ie: #/room/roomId/eventId (eventId of a thread message)
             if (thread?.rootEvent && !initialEvent?.isThreadRoot) {
                 dis.dispatch<ShowThreadPayload>({
                     action: Action.ShowThread,
@@ -719,16 +721,6 @@ export class RoomView extends React.Component<IRoomProps, IRoomState> {
                 newState.initialEventId = initialEventId;
                 newState.isInitialEventHighlighted = this.context.roomViewStore.isInitialEventHighlighted();
                 newState.initialEventScrollIntoView = this.context.roomViewStore.initialEventScrollIntoView();
-
-                if (thread?.rootEvent && initialEvent?.isThreadRoot) {
-                    dis.dispatch<ShowThreadPayload>({
-                        action: Action.ShowThread,
-                        rootEvent: thread.rootEvent,
-                        initialEvent,
-                        highlighted: this.context.roomViewStore.isInitialEventHighlighted(),
-                        scroll_into_view: this.context.roomViewStore.initialEventScrollIntoView(),
-                    });
-                }
             }
         }