Shared chest, menu after a game, dialogs over 16:9 screens

- Shared chest: emptied and not saved from the moment a save game is read
  until it reloads; a hero saved inside a load wrote the new world's
  objects (stale ids) as the chest's items.
- Main menu after a game: shown 16:9 screens are tracked on the menu thread
  only and expire after 2 frames; a destroyed in-game window kept the menu
  unframed (old pictures, frame at the left).
- Dialogs over a 16:9 screen in the main menu are centred, their dimming
  covers the screen.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

docs/screens.md

@@ -75,3 +75,16 @@ window's own pictures removed.
 
 - Spielen (the load window, cUI_Savegame): docs/characters.md, "Spielen
   screen".
+
+## Fixes (2026-10-21)
+
+- The main menu came back unframed (old pictures, frame at the left) after a
+  game: the set of shown 16:9 screens kept a window of the in-game UI that
+  was destroyed while shown. Now only screens drawn on the menu thread count,
+  and an entry expires after 2 menu frames without being drawn
+  (`screen::BeginMenuFrame`).
+- Dialogs over a 16:9 screen in the main menu (e.g. "Spielstand laden?") sat
+  at the left with the dimming 1024 wide: `hud::OffsetFor` gave every window
+  offset 0 while the menu showed. Now only while the menu frame is drawn
+  centred (it shifts the windows itself); otherwise dialogs are centred and
+  their full-layout dimming stretched, as in a game.

docs/shared-chest.md

@@ -70,3 +70,18 @@ was empty after loading another character (in-game saves don't call saveHero).
 - loadHero's extra fix-up for some item classes (`0x5beaa0` / `0x5d3a20`,
   item classes 5, 6, 8, 0xd, 0x11..0x19, 0x1b, 0x1d) is not repeated.
 - Multiplayer: not supported.
+
+## Items replaced by a world's (fixed 2026-10-21)
+
+Reported: the shared chest's items were gone, other items (potions, gear) in
+their cells. The grid holds object ids. A save game loaded into the running
+engine (Esc "Laden", cEngine::Load from the render loop 0x60e68d) replaces
+all objects, so until the chest reloads on the next tick its ids name the new
+world's objects. A hero saved inside that load (characters.cpp Engine_Load: a
+migrated character's first load makes its world hero the shared hero with
+SaveHero) wrote the shared chest, i.e. those objects, into
+shared_chest.json; the next tick loaded them as the chest. Now the chest is
+emptied and marked unloaded as soon as a save game is read or a game starts
+(RequestLoad), so no save writes it before it is loaded again. The user's
+chest was restored from the 2026-10-19 backup (the broken file kept as
+backup/shared_chest.broken-2026-10-21.json).

src/mods/hud.cpp

@@ -53,14 +53,21 @@ thread_local bool g_eventShifted = false;
 // Canvas: a 16:9 screen (kCanvasWidth), centred.
 enum class Anchor { Center, Right, Screen, Canvas };
 
+// Offset of the main menu's 1024 frame while it is drawn centred (set each
+// menu frame by RenderMenuFrame; 0 while a 16:9 screen draws itself).
+std::atomic<int> g_menuFrameDx = 0;
+
 int OffsetFor(Anchor anchor) {
     static const bool enabled = re::ConfigInt("hud", "Enabled", 1) != 0;
     const int width = mods::widescreen::RenderWidth();
     if (anchor == Anchor::Canvas) {
         return width > kCanvasWidth ? (width - kCanvasWidth) / 2 : 0;
     }
-    if (!enabled || width <= kLayoutWidth || mods::widescreen::IsClassicFrame() ||
-        mods::widescreen::MenuIsShowing() || anchor == Anchor::Screen) {
+    // The main menu's frame shifts the windows in it; over a 16:9 screen
+    // (no frame) dialogs are centred like in a game (user, 2026-10-21).
+    const bool inMenuFrame = mods::widescreen::MenuIsShowing() && g_menuFrameDx != 0;
+    if (!enabled || width <= kLayoutWidth || mods::widescreen::IsClassicFrame() || inMenuFrame ||
+        anchor == Anchor::Screen) {
         return 0;
     }
     return anchor == Anchor::Center ? (width - kLayoutWidth) / 2 : width - kLayoutWidth;
@@ -868,10 +875,6 @@ int HandleCentred(void* event, int (*body)(void* context), void* context) {
     return body(context);
 }
 
-// Offset of the main menu's 1024 frame while it is drawn centred (set each
-// menu frame by RenderMenuFrame; 0 while a 16:9 screen draws itself).
-std::atomic<int> g_menuFrameDx = 0;
-
 void SetHiddenTextures(void* const* surfaces, int count) {
     for (int i = 0; i < kHiddenTextureMax; ++i) {
         g_hiddenTextures[i].store(i < count ? surfaces[i] : nullptr, std::memory_order_relaxed);

src/mods/screen.cpp

@@ -4,8 +4,7 @@
 
 #include <algorithm>
 #include <atomic>
-#include <mutex>
-#include <set>
+#include <map>
 #include <vector>
 
 #include <windows.h>
@@ -46,15 +45,22 @@ constexpr int kHeadingHeight = 30;
 // frames).
 std::atomic<unsigned> g_frame{1};
 
-// The windows whose screen is shown: the main menu's frame is not drawn
-// centred while any is (the screen draws itself across the width).
-std::mutex g_shownLock;
-std::set<const void*> g_shown;
+// The windows whose screen is shown on the menu thread, with the menu frame
+// they were last drawn in: the main menu's frame is not drawn centred while
+// any is (the screen draws itself across the width). Entries not drawn for
+// kShownFrames frames are dropped: the UI is rebuilt when a game starts or
+// ends, and a window destroyed while shown kept the menu from being framed
+// (user, 2026-10-21: "the old main menu is rendering again"). Menu thread only.
+constexpr unsigned kShownFrames = 2;
+unsigned g_menuFrame = 0;
+std::map<const void*, unsigned> g_shown;
 
 void NoteShown(const void* window, bool shown) {
-    std::lock_guard guard(g_shownLock);
+    if (!widescreen::IsMenuThread()) {
+        return;
+    }
     if (shown) {
-        g_shown.insert(window);
+        g_shown[window] = g_menuFrame;
     } else {
         g_shown.erase(window);
     }
@@ -91,11 +97,6 @@ void HidePictures() {
     hud::SetHiddenTextures(surfaces.data(), static_cast<int>(surfaces.size()));
 }
 
-bool ShownAny() {
-    std::lock_guard guard(g_shownLock);
-    return !g_shown.empty();
-}
-
 // The game's logo top left (user, 2026-10-21: "the bright blueish one"),
 // kLogoMargin from the edges: FX_SACREDLOGO.TGA, the emblem (horns around a
 // ring of runes) glowing blue on black, no alpha, added onto the background as
@@ -134,8 +135,10 @@ void DrawRockWall(void* device, float width, float height) {
 
 } // namespace
 
-bool AnyShown() {
-    return ShownAny();
+bool BeginMenuFrame() {
+    ++g_menuFrame;
+    std::erase_if(g_shown, [](const auto& entry) { return g_menuFrame - entry.second > kShownFrames; });
+    return !g_shown.empty();
 }
 
 void DrawBackground(void* device) {
@@ -261,7 +264,7 @@ uint32_t __fastcall UiManager_Render(void* self, void* edx, uint32_t argument) {
     }
     auto* driver = *reinterpret_cast<DxDriver7**>(addr::g_dxDriver);
     void* device = driver ? driver->device : nullptr;
-    const bool framed = !screen::AnyShown();
+    const bool framed = !screen::BeginMenuFrame();
     if (framed && device) {
         screen::DrawBackground(device);
     }

src/mods/screen.h

@@ -50,8 +50,9 @@ constexpr uint32_t kRowSelectedColour = 0xc0604818;
 // The background of the menu screens across the whole render target (also
 // beside the main menu's centred frame and full-screen windows in a game).
 void DrawBackground(void* device);
-// Whether a screen is shown (the main menu then does not draw centred).
-bool AnyShown();
+// Called once per main menu frame (menu thread): whether a screen is shown
+// (the main menu then does not draw centred).
+bool BeginMenuFrame();
 
 // Draws the screen of `window`: the background across the whole render
 // target, then body(context) in canvas coordinates.

src/mods/sharedchest.cpp

@@ -166,9 +166,17 @@ void Load() {
 }
 
 // A session started or a save game was loaded into it (its objects replace
-// the old ones): (re)load on the next tick with a hero.
+// the old ones): (re)load on the next tick with a hero. Until then the grid's
+// ids are stale (they name the new world's objects) and nothing is saved: a
+// hero saved inside the load (characters.cpp, Engine_Load, a migrated
+// character's first load) wrote them into the file, the chest's items
+// replaced by the world's (user, 2026-10-21).
 void RequestLoad() {
+    g_loaded = false;
     g_loadPending = true;
+    if (g_constructed) {
+        ClearGrid();
+    }
 }
 
 // The chest grid's place and size, as the cUI_Chest constructor sets them for