diff --git a/src-tauri/src/menu.rs b/src-tauri/src/menu.rs
index 909118a4..676a8664 100644
--- a/src-tauri/src/menu.rs
+++ b/src-tauri/src/menu.rs
@@ -781,6 +781,9 @@ pub fn spec(os: Os) -> Vec<Entry> {
                 act("editor.splitDown", "Split Down"),
                 act("editor.unsplit", "Unsplit"),
                 act("editor.moveToOppositeGroup", "Move to Opposite Group"),
+                act("editor.openInOppositeGroup", "Open in Opposite Group"),
+                act("editor.changeSplitOrientation", "Change Splitter Orientation"),
+                act("editor.unsplitAll", "Unsplit All"),
                 act("editor.nextSplitter", "Go to Next Splitter"),
                 act("editor.prevSplitter", "Go to Previous Splitter"),
             ],
diff --git a/src/editor/core/actions.ts b/src/editor/core/actions.ts
index 018dd05b..2c8c570c 100644
--- a/src/editor/core/actions.ts
+++ b/src/editor/core/actions.ts
@@ -904,6 +904,30 @@ export function registerEditorActions(): () => void {
       when: "editorSplit",
       run: () => ctrl.unsplit(useTabs.getState().activePane),
     },
+    {
+      id: "editor.unsplitAll",
+      title: "Unsplit All",
+      category: "Window",
+      when: "editorSplit",
+      run: () => ctrl.unsplitAll(useTabs.getState().activePane),
+    },
+    {
+      id: "editor.changeSplitOrientation",
+      title: "Change Splitter Orientation",
+      category: "Window",
+      when: "editorSplit",
+      run: () => ctrl.changeSplitOrientation(useTabs.getState().activePane),
+    },
+    {
+      id: "editor.openInOppositeGroup",
+      title: "Open in Opposite Group",
+      category: "Window",
+      when: TABS_WHEN,
+      run: () => {
+        const t = activePaneTab();
+        if (t) ctrl.openInOpposite(t.paneId, t.tabId);
+      },
+    },
     {
       id: "editor.copyPath",
       title: "Copy Path",
diff --git a/src/editor/core/controller.test.ts b/src/editor/core/controller.test.ts
index 8079c4f8..21ead41a 100644
--- a/src/editor/core/controller.test.ts
+++ b/src/editor/core/controller.test.ts
@@ -65,6 +65,23 @@ describe("EditorController", () => {
     expect(openFilePaths(useTabs.getState())).toEqual(["/p/a.ts", "/p/b.ts"]);
   });
 
+  it("opens a copy of a tab in the opposite group, splitting when there is none", async () => {
+    ctrl = new EditorController(createMemoryBackend({ "/p/a.ts": "", "/p/b.ts": "" }));
+    ctrl.start();
+    await ctrl.openFile("/p/a.ts", { focus: false });
+    await ctrl.openFile("/p/b.ts", { focus: false });
+    const paths = (paneId: string) => useTabs.getState().panes[paneId]!.tabs.map((t) => t.input.path);
+    const first = useTabs.getState().activePane;
+    const tabA = useTabs.getState().panes[first]!.tabs[0]!.id;
+    ctrl.openInOpposite(first, tabA);
+    const second = useTabs.getState().activePane;
+    expect(second).not.toBe(first);
+    expect(paths(second)).toEqual(["/p/a.ts"]);
+    ctrl.openInOpposite(first, useTabs.getState().panes[first]!.tabs[1]!.id);
+    expect(paths(second)).toEqual(["/p/a.ts", "/p/b.ts"]);
+    expect(paths(first)).toEqual(["/p/a.ts", "/p/b.ts"]);
+  });
+
   it("reopens the LightEdit files the next time a window switches to LightEdit", async () => {
     ctrl = new EditorController(createMemoryBackend({ "/x/a.txt": "a", "/y/b.md": "b" }));
     ctrl.start();
diff --git a/src/editor/core/controller.ts b/src/editor/core/controller.ts
index a19d8c70..deca0802 100644
--- a/src/editor/core/controller.ts
+++ b/src/editor/core/controller.ts
@@ -31,6 +31,7 @@ import { fileIconName, showContextMenu, type MenuItem } from "@/ui";
 import { usePlatform } from "@/platform/platformInfo";
 import {
   activateTab,
+  changeSplitOrientation,
   closeAll,
   closeKey,
   closeOthers,
@@ -57,6 +58,7 @@ import {
   splitPane,
   tabOptions,
   togglePin,
+  unsplitAll,
   type SplitEdge,
   type Tab,
   type TabsState,
@@ -1009,6 +1011,30 @@ export class EditorController implements SlotHost {
   unsplit(paneId: string) {
     this.apply((s) => removePane(s, paneId));
   }
+  unsplitAll(paneId: string) {
+    this.apply((s) => unsplitAll(s, paneId));
+    this.focus();
+  }
+  changeSplitOrientation(paneId: string) {
+    this.apply((s) => changeSplitOrientation(s, paneId));
+  }
+  /** IDEA "Open in Opposite Group": the tab stays and a copy opens next door (or in a new split). */
+  openInOpposite(paneId: string, tabId: string) {
+    const s = useTabs.getState();
+    const tab = s.panes[paneId]?.tabs.find((t) => t.id === tabId);
+    if (!tab) return;
+    const target = neighbourPane(s, paneId);
+    if (!target) {
+      this.activate(paneId, tabId, false);
+      return this.split(paneId, "row");
+    }
+    const r = openTab(s, target, tab.input);
+    useTabs.setState(r.state, true);
+    void this.ensureSlot(r.tabId, { from: this.slots.get(tabId) }).then((slot) => {
+      if (slot?.view) slot.focus();
+      else if (slot) slot.wantsFocus = true;
+    });
+  }
 
   closeActiveTab() {
     const s = useTabs.getState();
@@ -1183,7 +1209,10 @@ export class EditorController implements SlotHost {
       ...(split
         ? ([
             { label: "Move to Opposite Group", run: () => this.moveToOpposite(paneId, tab.id) },
+            { label: "Open in Opposite Group", run: () => this.openInOpposite(paneId, tab.id) },
+            { label: "Change Splitter Orientation", run: () => this.changeSplitOrientation(paneId) },
             { label: "Unsplit", run: () => this.unsplit(paneId) },
+            { label: "Unsplit All", run: () => this.unsplitAll(paneId) },
           ] as MenuItem[])
         : []),
       { kind: "separator" },
diff --git a/src/editor/core/model/model.test.ts b/src/editor/core/model/model.test.ts
index b432a8eb..062afa2c 100644
--- a/src/editor/core/model/model.test.ts
+++ b/src/editor/core/model/model.test.ts
@@ -1,5 +1,6 @@
 import { describe, expect, it } from "vitest";
 import {
+  changeSplitOrientation,
   closeAll,
   closeKey,
   closeOthers,
@@ -19,6 +20,7 @@ import {
   splitPane,
   tabOptions,
   togglePin,
+  unsplitAll,
   type TabsState,
 } from "./tabs";
 import { NavigationHistory } from "./navHistory";
@@ -168,6 +170,29 @@ describe("tab model", () => {
     expect(s.layout).toEqual({ kind: "pane", paneId: split.paneId });
   });
 
+  it("flips the orientation of a split and unsplits everything", () => {
+    let s = open(initialTabsState(), "a");
+    const first = s.activePane;
+    const right = splitPane(s, first, "row");
+    const below = splitPane(right.state, right.paneId, "column");
+    s = below.state;
+    const dirs = (st: TabsState) =>
+      st.layout.kind === "split"
+        ? [st.layout.dir, ...st.layout.children.map((c) => (c.kind === "split" ? c.dir : "pane"))]
+        : [];
+    expect(dirs(s)).toEqual(["row", "pane", "column"]);
+    // The nested split turns side by side and merges into the outer row.
+    s = changeSplitOrientation(s, below.paneId);
+    expect(dirs(s)).toEqual(["row", "pane", "pane", "pane"]);
+    s = changeSplitOrientation(s, first);
+    expect(dirs(s)).toEqual(["column", "pane", "pane", "pane"]);
+    expect(changeSplitOrientation(open(initialTabsState(), "x"), "nope").layout.kind).toBe("pane");
+    s = unsplitAll(s, right.paneId);
+    expect(paneIds(s)).toEqual([right.paneId]);
+    expect(s.activePane).toBe(right.paneId);
+    expect(labels(s)).toEqual(["a"]);
+  });
+
   it("closes a key everywhere and cycles tabs", () => {
     let s = initialTabsState();
     s = open(s, "a");
diff --git a/src/editor/core/model/tabs.ts b/src/editor/core/model/tabs.ts
index 0ed7a538..2dcb9ee6 100644
--- a/src/editor/core/model/tabs.ts
+++ b/src/editor/core/model/tabs.ts
@@ -437,6 +437,30 @@ export function removePane(s: TabsState, paneId: string): TabsState {
   return { ...s, layout, panes, activePane };
 }
 
+/** Flips the split that directly holds `paneId` between side by side and stacked. */
+export function changeSplitOrientation(s: TabsState, paneId: string): TabsState {
+  let changed = false;
+  const flipped = mapLayout(s.layout, (n) => {
+    if (n.kind !== "split" || !n.children.some((c) => c.kind === "pane" && c.paneId === paneId)) return n;
+    changed = true;
+    const dir = n.dir === "row" ? "column" : "row";
+    return { ...n, dir, children: n.children.flatMap((c) => (c.kind === "split" && c.dir === dir ? c.children : [c])) };
+  })!;
+  // The parent flattens a flipped split that now runs its way; the flipped one absorbs its children.
+  return changed ? { ...s, layout: flipped } : s;
+}
+
+/** Removes every pane except `keepPane`. */
+export function unsplitAll(s: TabsState, keepPane: string): TabsState {
+  if (!s.panes[keepPane]) return s;
+  return {
+    ...s,
+    layout: { kind: "pane", paneId: keepPane },
+    panes: { [keepPane]: s.panes[keepPane] },
+    activePane: keepPane,
+  };
+}
+
 /** The pane right of / below `paneId`, if any (for "open to the side"). */
 export function neighbourPane(s: TabsState, paneId: string): string | null {
   const order = paneIds(s);
diff --git a/src/platform/locales/en.json b/src/platform/locales/en.json
index 8c4182d0..7034ea9e 100644
--- a/src/platform/locales/en.json
+++ b/src/platform/locales/en.json
@@ -398,6 +398,9 @@
   "menu.editor.closeAllTabs": "Close All Tabs",
   "menu.editor.reopenClosedTab": "Reopen Closed Tab",
   "menu.editor.moveToOppositeGroup": "Move to Opposite Group",
+  "menu.editor.openInOppositeGroup": "Open in Opposite Group",
+  "menu.editor.changeSplitOrientation": "Change Splitter Orientation",
+  "menu.editor.unsplitAll": "Unsplit All",
   "menu.navigate.showFilePath": "File Path",
   "menu.navigate.customRegion": "Custom Folding…",
   "menu.code.showErrorDescription": "Error Description",
diff --git a/src/platform/locales/text/zh.json b/src/platform/locales/text/zh.json
index 7472ad9d..fb0ace45 100644
--- a/src/platform/locales/text/zh.json
+++ b/src/platform/locales/text/zh.json
@@ -225,6 +225,7 @@
   "Caret should be positioned at the name of the element to be refactored": "光标应位于要重构的元素名称上",
   "Cascade": "级联",
   "Case sensitive": "区分大小写",
+  "Change Splitter Orientation": "更改拆分方向",
   "Change Signature…": "更改签名…",
   "Change actions": "更改操作",
   "Change font size with Command+Mouse Wheel": "使用 Command+鼠标滚轮更改字体大小",
@@ -1271,6 +1272,7 @@
   "Open in Browser": "在浏览器中打开",
   "Open in Find Tool Window": "在“查找”工具窗口中打开",
   "Open in Find Window": "在查找窗口中打开",
+  "Open in Opposite Group": "在相对组中打开",
   "Open in New Window": "在新窗口中打开",
   "Open in Terminal": "在终端中打开",
   "Open in editor": "在编辑器中打开",
@@ -2154,6 +2156,7 @@
   "Unshelve Changes": "取消搁置更改",
   "Unshelve…": "取消搁置…",
   "Unsplit": "取消拆分",
+  "Unsplit All": "全部取消拆分",
   "Unstage": "取消暂存",
   "Unstash Changes…": "取消储藏更改…",
   "Update": "更新",
diff --git a/src/platform/locales/zh.json b/src/platform/locales/zh.json
index 52855c67..38e55b6d 100644
--- a/src/platform/locales/zh.json
+++ b/src/platform/locales/zh.json
@@ -398,6 +398,9 @@
   "menu.editor.closeAllTabs": "关闭所有标签页",
   "menu.editor.reopenClosedTab": "重新打开已关闭的标签页",
   "menu.editor.moveToOppositeGroup": "移动到另一组",
+  "menu.editor.openInOppositeGroup": "在相对组中打开",
+  "menu.editor.changeSplitOrientation": "更改拆分方向",
+  "menu.editor.unsplitAll": "全部取消拆分",
   "menu.navigate.showFilePath": "文件路径",
   "menu.navigate.customRegion": "自定义折叠…",
   "menu.code.showErrorDescription": "错误描述",