Release v0.6.20: edit history images and share smooth wheel handling

CMakeLists.txt

@@ -1,5 +1,5 @@
 cmake_minimum_required(VERSION 3.24)
-project(KSwitcher VERSION 0.6.18 LANGUAGES CXX RC)
+project(KSwitcher VERSION 0.6.20 LANGUAGES CXX RC)
 if(NOT WIN32)
   message(FATAL_ERROR "KSwitcher uses native Windows APIs")
 endif()
@@ -17,6 +17,8 @@ set_target_properties(KSwitcherConfig PROPERTIES OUTPUT_NAME "KSwitcher.Config")
 target_compile_definitions(KSwitcherConfig PRIVATE KS_CONFIG_APP)
 target_link_libraries(KSwitcherConfig PRIVATE kscore)
 add_executable(KSwitcherTests tests/tests.cpp)
+add_executable(KSwitcherScrollTests tests/scroll.cpp)
+target_link_libraries(KSwitcherScrollTests PRIVATE kscore)
 target_link_libraries(KSwitcherTests PRIVATE kscore)
 add_executable(KSwitcherIntegration tests/integration.cpp src/screenshot_launcher.cpp src/screenshot_activation.cpp src/app.cpp src/screenshot_notifications.cpp src/screenshot.cpp src/configuration.cpp src/ui.cpp resources/app.rc)
 target_link_libraries(KSwitcherIntegration PRIVATE kscore)
@@ -39,7 +41,7 @@ endif()
 add_executable(KSwitcherOcrTests tests/ocr.cpp src/screenshot_launcher.cpp src/screenshot_activation.cpp src/app.cpp src/screenshot_notifications.cpp src/screenshot.cpp src/configuration.cpp src/ui.cpp resources/app.rc)
 target_link_libraries(KSwitcherOcrTests PRIVATE kscore)
 if(MSVC)
-  set_property(TARGET kscore KSwitcher KSwitcherConfig KSwitcherScreenshot KSwitcherTests KSwitcherIntegration KSwitcherInputTests KSwitcherOcrTests PROPERTY MSVC_RUNTIME_LIBRARY "MultiThreaded$<$<CONFIG:Debug>:Debug>")
+  set_property(TARGET kscore KSwitcher KSwitcherConfig KSwitcherScreenshot KSwitcherTests KSwitcherScrollTests KSwitcherIntegration KSwitcherInputTests KSwitcherOcrTests PROPERTY MSVC_RUNTIME_LIBRARY "MultiThreaded$<$<CONFIG:Debug>:Debug>")
   target_compile_options(kscore PRIVATE /W4 /utf-8)
   target_compile_options(KSwitcher PRIVATE /W4 /utf-8)
   target_compile_options(KSwitcherConfig PRIVATE /W4 /utf-8)
@@ -49,12 +51,14 @@ else()
   target_link_options(KSwitcherConfig PRIVATE -municode -static -static-libgcc -static-libstdc++)
   target_link_options(KSwitcherScreenshot PRIVATE -municode -static -static-libgcc -static-libstdc++)
   target_link_options(KSwitcherTests PRIVATE -static -static-libgcc -static-libstdc++)
+  target_link_options(KSwitcherScrollTests PRIVATE -static -static-libgcc -static-libstdc++)
   target_link_options(KSwitcherIntegration PRIVATE -static -static-libgcc -static-libstdc++)
   target_link_options(KSwitcherInputTests PRIVATE -static -static-libgcc -static-libstdc++)
   target_link_options(KSwitcherOcrTests PRIVATE -static -static-libgcc -static-libstdc++)
 endif()
 enable_testing()
 add_test(NAME native-regressions COMMAND KSwitcherTests)
+add_test(NAME scroll-regressions COMMAND KSwitcherScrollTests)
 add_test(NAME input-regressions COMMAND KSwitcherInputTests)
 add_test(NAME screenshot-ui-regressions COMMAND KSwitcherScreenshotUITests)
 add_test(NAME updater-regressions COMMAND powershell.exe -NoProfile -ExecutionPolicy Bypass -File "${CMAKE_CURRENT_SOURCE_DIR}/tests/update.ps1" -Executable "$<TARGET_FILE:KSwitcher>")

README.md

@@ -226,11 +226,16 @@ thumbnails and source labels aligned with the scaled fonts and spacing.
   If the editor's word boundary differs from the recorded typing, it falls back to paced character
   selection: Teams can coalesce a burst of Shift+Left events into just one character.
 - Clipboard snapshot/restoration with concurrent-copy, foreground and input-version checks.
+  A silently dropped copy is retried up to three total attempts while the clipboard and input
+  context remain unchanged. Temporary transaction contents are excluded from Windows clipboard
+  history and cloud synchronization. Paste is not blindly retried.
 - Case cycling, Russian/Ukrainian transliteration, verified undo and repeated conversion.
 - Text snippets across layouts, multiline insertion and a verified `{cursor}` position;
   `{enter}` presses Enter after insertion and cursor placement (once per marker), before buffered typing resumes.
   For example, `rider .{enter}` inserts `rider .` and presses Enter.
   Automatic correction is suppressed during snippet expansion and for typing buffered by that expansion; the global setting is preserved.
+  If the trigger cannot be verified after the copy attempts, it is preserved, queued typing resumes,
+  and no Enter action is sent.
   `{{cursor}}` and `{{enter}}` insert literal markers. Snippets are stored as plaintext settings, as in [Typlo](https://github.com/bitcodepro/Typlo).
 - Clipboard history for text, HTML/RTF, file lists, DIB and PNG images; plain-text paste;
   full-text search, pinning, deletion, full text viewing and image previews.
@@ -273,6 +278,21 @@ existing saved shortcuts are preserved. While KSwitcher runs, this binding opens
 
 History controls: Enter to paste, Shift+Enter for plain text, Ctrl+1…9 for quick paste,
 Ctrl+P to pin/unpin, Delete to delete, Ctrl+O for the full item, Escape to hide.
+For an image, **Edit image**, **Ctrl+O**, or **Edit image in screenshot editor**
+in the context menu opens the original image in the built-in screenshot editor.
+Annotate it there, then copy the result. Opening the editor leaves the
+clipboard and original history entry unchanged. Text items still open as text;
+Enter and double-click still paste the selected item.
+
+Local builds made with `build.ps1` show **[LOCAL DEV]** in window titles and
+the tray tooltip. The marker is enabled by `.local-dev` beside the executable;
+release packages do not include that marker.
+
+Fast/inertial wheel events use a shared batching handler in history, layout and
+snippet lists, the log table, multiline text/details fields, combo boxes and
+scrollable settings windows. High-resolution partial wheel steps are retained.
+History pauses new preview loads while scrolling and keeps visible thumbnails
+cached, preventing continuous flicker and needless redraws.
 Pressing the history shortcut a second time pastes the second-most-recent item.
 
 ## Data and migration

Release/README.md

@@ -1,23 +1,24 @@
 # Latest Windows release
 
-## v0.6.18 — 2026-10-31
+## v0.6.20 — 2026-10-31
 
 ## Changes
-- Verify the actual editor text after manual conversion using read-only Windows Accessibility, without moving the caret, changing selection or copying again. Record unchanged calculations, original text remaining, unexpected readback and unavailable verification separately.
+- Open clipboard-history images in the built-in screenshot editor with **Edit image**, **Ctrl+O**, or **Edit image in screenshot editor** in the context menu. PNG, DIB and DIBV5 open at full resolution through an encrypted local cache, without requiring notifications or changing the clipboard/original history entry. Copy the annotated result explicitly from the editor.
-- Replace the event-only diagnostic list with sortable Time, Program, Command, Source layout, Target layout and Result columns; add program/command/result filters and a separate panel with original, expected and read-back text and operation context.
+- Fix continuous history flicker by keeping visible previews cached, invalidating only completed preview rows and preserving the top entry across background refreshes.
-- Keep successful operations only in a bounded in-memory context (40 events, 30 seconds). Only problem operations create file rows; verified successes do not fill the log. Diagnostics work in normal Release builds and the additional readback check is skipped when logging is disabled.
+- Handle fast/inertial wheels through one shared batching mechanism for history, layout/snippet lists, the log table, multiline text/details fields, combo boxes and scrollable settings windows. Preserve partial wheel deltas, clamp list boundaries and pause new history previews until scrolling stops.
-- Refresh English and Ukrainian Wiki documentation through v0.6.18, including previously undocumented snippet, updater and constrained-pencil changes since v0.6.14.
+- Mark local developer builds with **[LOCAL DEV]** in window titles and the tray tooltip. Release packages omit the development marker. This does not create a separate data profile.
-
+- Right-clicking a history entry selects that entry before showing its actions. Enter and double-click continue to paste; text items still open in the full-text viewer.
-## Limitations
-Some editors do not expose their text through Windows Accessibility. Changed focus, protected or unsupported controls, provider-specific character units, delayed text updates and the 4096-character readback limit can prevent verification; these cases are recorded as unverified rather than successful. Historical unstructured entries remain readable without retroactive filter fields.
 
 ## Validation
-Passed 230 native regression checks, 472 input/UI checks, screenshot editor UI and notification registration checks, 48 updater checks, updater progress checks, 45 isolated configurator process checks, conversion-specific editor integration and diagnostic viewer checks. Verified that 1000 successful operations create no log file and that a subsequent failure creates one row with bounded context. The broader editor integration suite still intermittently fails in snippet Enter/concurrent-input scenarios; similar failures reproduce with the pre-change code.
+Passed 406 native regressions, 473 input/UI checks, shared wheel batching tests, screenshot editor UI, notification registration, 48 updater checks and updater progress checks. Manual testing confirmed image editing from history and resolved clipboard flicker and Logitech inertial-wheel beeping. Shared wheel tests cover lists, edits, tables, combo boxes and windows, partial steps, large bursts, selection preservation and list boundaries.
+
+## Limitations
+Image decoding or a normalized image larger than the 128 MiB editor-transfer limit can prevent opening; an error is shown. Existing clipboard, OCR and editor privilege limitations remain. The wheel over screenshot annotations changes size/thickness rather than scrolling.
 
 **Upgrade:** choose Update in the tray menu. Legacy v0.3.0–v0.4.1 clients first receive the v0.4.2 compatibility bridge, then the current full release. v0.2.3 and earlier require manual installation.
-For manual installation, exit KSwitcher and extract the entire ZIP into its installation folder. Keep personal `data/` and customized dictionaries.
+For manual installation, exit KSwitcher, close screenshot editors and extract the entire ZIP into its installation folder. Keep personal `data/` and customized dictionaries.
 
-Download **KSwitcher-win-x64.zip** with **SHA256SUMS.txt**. The package contains all three executables, a release manifest, offline dictionaries, documentation and license notices. It contains no personal settings, clipboard history, Tesseract installation or language models.
+Download **KSwitcher-win-x64.zip** with **SHA256SUMS.txt**. The package contains all three executables, a release manifest, offline dictionaries, documentation and license notices. It contains no personal settings, clipboard history, development marker, Tesseract installation or language models.
 
 Build and package:
 

Release/SHA256SUMS.txt

@@ -1 +1 @@
-3e76d8a566c623a3084c00cc909f4cc7c8a6edb38f9c06adbb32edfd4cfcb5b7  KSwitcher-win-x64.zip
+0b3c4fd1346d0b4eeb73d276193c5d2789fd32986c3cc75384cf489f23629678  KSwitcher-win-x64.zip

build.ps1

@@ -10,6 +10,8 @@ $outDir = Join-Path $root 'build'
 New-Item -ItemType Directory -Force $outDir | Out-Null
 $executablePath = if ($Stage) { Join-Path $outDir 'staged\KSwitcher.exe' } else { Join-Path $outDir 'KSwitcher.exe' }
 New-Item -ItemType Directory -Force (Split-Path $executablePath) | Out-Null
+Set-Content -LiteralPath (Join-Path $outDir '.local-dev') -Value 'Local development build' -Encoding ascii
+Set-Content -LiteralPath (Join-Path (Split-Path $executablePath) '.local-dev') -Value 'Local development build' -Encoding ascii
 Push-Location $root
 try {
     $common = @('-std=c++20','-Os','-DNDEBUG','-DUNICODE','-D_UNICODE','-DWIN32_LEAN_AND_MEAN','-DNOMINMAX','-D_WIN32_WINNT=0x0A00','-Wall','-Wextra','-Wno-missing-field-initializers','-Isrc','-Ivendor','-ffunction-sections','-fdata-sections')
@@ -39,6 +41,10 @@ try {
     if ($LASTEXITCODE) { throw 'Screenshot link failed' }
     Copy-Item -LiteralPath $screenshotPath -Destination build/release/KSwitcher.Screenshot.exe -Force
     if ($Test) {
+        & $compiler @common tests/scroll.cpp @libs -static -s -o build/KSwitcherScrollTests.exe
+        if ($LASTEXITCODE) { throw 'Scroll test build failed' }
+        & .\build\KSwitcherScrollTests.exe
+        if ($LASTEXITCODE) { throw 'Scroll tests failed' }
         & $compiler @common tests/tests.cpp build/core.o build/platform.o build/autostart.o build/autocorrect.o build/storage.o build/ocr.o build/richtext.o build/update.o @libs -static -s -o build/KSwitcherTests.exe
         if ($LASTEXITCODE) { throw 'Test build failed' }
         & .\build\KSwitcherTests.exe

resources/app.rc

@@ -9,8 +9,8 @@ IDC_SCREENSHOT_PENCIL CURSOR "icons/lucide/pencil.cur"
 1 RT_MANIFEST "app.manifest"
 201 RCDATA "update.ps1"
 1 VERSIONINFO
- FILEVERSION 0,6,18,0
+ FILEVERSION 0,6,20,0
- PRODUCTVERSION 0,6,18,0
+ PRODUCTVERSION 0,6,20,0
  FILEOS VOS_NT_WINDOWS32
  FILETYPE VFT_APP
 BEGIN
@@ -20,7 +20,7 @@ BEGIN
   BEGIN
    VALUE "FileDescription", "KSwitcher — native keyboard and clipboard utility"
    VALUE "ProductName", "KSwitcher"
-   VALUE "FileVersion", "0.6.18"
+   VALUE "FileVersion", "0.6.20"
   END
  END
  BLOCK "VarFileInfo"

src/app.cpp

@@ -124,7 +124,13 @@ class Transaction
     {
         check();
         adopted.clear();
-        app.ownSequence = expected = writeClipboard(app.window, c);
+        // These are temporary transaction contents, not a user's clipboard entry.
+        // In particular, do not invite the Windows history service to read our
+        // sentinel while the target editor is trying to open the clipboard.
+        auto temporary = c;
+        const std::wstring exclusion = L"ExcludeClipboardContentFromMonitorProcessing";
+        temporary.formats.push_back({RegisterClipboardFormatW(exclusion.c_str()), exclusion, Bytes{0}});
+        app.ownSequence = expected = writeClipboard(app.window, temporary);
         // A concurrent writer can win immediately after CloseClipboard, before we read its sequence.
         // Never adopt that writer's sequence as our own and paste its content.
         if (GetClipboardOwner() != app.window)
@@ -146,6 +152,8 @@ class Transaction
             return {};
         }
         ULONGLONG deadline = GetTickCount64() + 2000;
+        ULONGLONG retryAt = GetTickCount64() + 250;
+        unsigned attempts = 1;
         DWORD changed = before;
         ULONGLONG stable = 0;
         bool changedAgain = false;
@@ -162,6 +170,21 @@ class Transaction
             }
             if (changed != before && GetTickCount64() - stable >= 60)
                 break;
+            // Native editors can silently drop Ctrl+C if another process has
+            // the clipboard open. Retry only while our sentinel is untouched;
+            // never overwrite a copy result or another application's content.
+            if (changed == before && attempts < 3 && GetTickCount64() >= retryAt &&
+                !GetOpenClipboardWindow())
+            {
+                check();
+                if (!valid() || GetClipboardSequenceNumber() != before)
+                    return {};
+                if (!chord(L'C', MOD_CONTROL))
+                    return {};
+                diagnosticEvent(L"Copy retry: clipboard unchanged after Ctrl+C");
+                ++attempts;
+                retryAt = GetTickCount64() + 250;
+            }
             Sleep(10);
         }
         if (changed == before || !valid())
@@ -410,7 +433,7 @@ void App::addTray()
     icon.uCallbackMessage = TrayMessage;
     icon.hIcon = (HICON)LoadImageW(instance, MAKEINTRESOURCEW(IDI_KSWITCHER), IMAGE_ICON,
                                    GetSystemMetrics(SM_CXSMICON), GetSystemMetrics(SM_CYSMICON), LR_SHARED);
-    wcscpy_s(icon.szTip, L"KSwitcher — keyboard layouts & clipboard");
+    wcscpy_s(icon.szTip, localBuildTitle(L"KSwitcher — keyboard layouts & clipboard").c_str());
     Shell_NotifyIconW(NIM_ADD, &icon);
     icon.uVersion = NOTIFYICON_VERSION_4;
     Shell_NotifyIconW(NIM_SETVERSION, &icon);

src/app.h

@@ -120,6 +120,7 @@ class App
 };
 void showHistory(App &, bool visible = true);
 void launchScreenshot(App &);
+void launchScreenshotEditor(App &, const Clip &);
 void refreshHistory(App &);
 void showSettings(App &, bool visible = true);
 void showLogs(App &);

src/history_preview.h

@@ -0,0 +1,17 @@
+#pragma once
+#include <map>
+#include <set>
+#include <string>
+
+namespace ks {
+// Keep the visible working set even in unusually tall windows. Never evict a
+// visible preview to admit another visible preview: that creates a paint loop.
+template<class T>
+void trimHistoryPreviews(std::map<std::wstring,T> &cache,
+                         const std::set<std::wstring> &visible, size_t limit=32)
+{
+    for(auto it=cache.begin(); cache.size()>limit && it!=cache.end();)
+        if(!visible.contains(it->first)) it=cache.erase(it);
+        else ++it;
+}
+}

src/platform.h

@@ -8,6 +8,16 @@
 
 namespace ks
 {
+inline std::wstring localBuildTitle(const std::wstring &title)
+{
+    static const bool development=[] {
+        wchar_t path[32768]{};
+        if(!GetModuleFileNameW(nullptr,path,std::size(path))) return false;
+        std::error_code error;
+        return std::filesystem::exists(std::filesystem::path(path).parent_path()/L".local-dev",error);
+    }();
+    return development?title+L" [LOCAL DEV]":title;
+}
 using Bytes = std::vector<unsigned char>;
 struct Format
 {

src/screenshot.cpp

@@ -841,7 +841,7 @@ void edit(HWND w, Capture &c)
     SetWindowLongPtrW(w,GWL_EXSTYLE,(GetWindowLongPtrW(w,GWL_EXSTYLE)|WS_EX_APPWINDOW)&~WS_EX_TOOLWINDOW);
     SetWindowLongPtrW(w,GWL_STYLE,WS_OVERLAPPEDWINDOW | WS_CLIPCHILDREN);
     auto title=L"KSwitcher — Screenshot #"+std::to_wstring(nextEditorIndex++);
-    SetWindowTextW(w,title.c_str());
+    SetWindowTextW(w,localBuildTitle(title).c_str());
     INITCOMMONCONTROLSEX statusControls{sizeof(statusControls),ICC_BAR_CLASSES};
     InitCommonControlsEx(&statusControls);
     CreateWindowExW(0,STATUSCLASSNAMEW,L"",WS_CHILD|WS_VISIBLE|SBARS_TOOLTIPS,

src/screenshot_launcher.cpp

@@ -1,13 +1,15 @@
 #include "app.h"
+#include "screenshot_notifications.h"
 
 namespace ks {
-void launchScreenshot(App &app)
+static void launch(App &app, const Clip *clip)
 {
     auto path=std::filesystem::path(executable()).parent_path()/L"KSwitcher.Screenshot.exe";
     if (!std::filesystem::exists(path))
         throw std::runtime_error("KSwitcher.Screenshot.exe is missing. Extract the complete application package.");
-    auto command=L"\""+path.wstring()+L"\" --auto-open-editor="+
+    auto command=L"\""+path.wstring()+L"\" ";
-        (app.settings.screenshotAutoOpenEditor?L"1":L"0");
+    if(clip) command+=L"--open kswitcher-screenshot:"+cacheScreenshotForEditor(*clip);
+    else command+=std::wstring(L"--auto-open-editor=")+(app.settings.screenshotAutoOpenEditor?L"1":L"0");
     if(app.settings.writeLog) command+=L" --write-log";
     STARTUPINFOW startup{sizeof(startup)};
     PROCESS_INFORMATION process{};
@@ -20,4 +22,6 @@ void launchScreenshot(App &app)
     CloseHandle(process.hThread);
     CloseHandle(process.hProcess);
 }
+void launchScreenshot(App &app) { launch(app,nullptr); }
+void launchScreenshotEditor(App &app,const Clip &clip) { launch(app,&clip); }
 }

src/screenshot_notifications.cpp

@@ -112,6 +112,19 @@ std::wstring escapeXml(const std::wstring &s)
     return result;
 }
 }
+std::wstring cacheScreenshotForEditor(const Clip &clip)
+{
+    // Normalize PNG/DIBV5 and other supported clipboard images at full resolution.
+    auto pixels=decodeImage(clip);
+    if(pixels.bgra.empty() || pixels.bgra.size()>128*1024*1024-sizeof(BITMAPINFOHEADER))
+        throw std::runtime_error("Image is too large for the screenshot editor");
+    auto dib=imageDib(pixels);
+    auto directory=cacheDirectory(); cleanCache(directory);
+    GUID guid{}; check(CoCreateGuid(&guid)); wchar_t value[40]{}; StringFromGUID2(guid,value,40);
+    std::wstring id(value+1,36);
+    atomicWrite(directory/(id+L".capture"),protect(dib.data));
+    return id;
+}
 Clip loadNotifiedScreenshot(const std::wstring &id)
 {
     if(!validScreenshotToken(id)) throw std::runtime_error("Invalid screenshot notification");

src/screenshot_notifications.h

@@ -8,4 +8,5 @@ int runScreenshotToastActivator();
 DWORD startScreenshotActivationListener();
 bool validScreenshotToken(const std::wstring &);
 Clip loadNotifiedScreenshot(const std::wstring &);
+std::wstring cacheScreenshotForEditor(const Clip &);
 }

src/ui.cpp

@@ -1,5 +1,7 @@
 #include "../resources/resource.h"
 #include "app.h"
+#include "history_preview.h"
+#include "ui_scroll.h"
 #include "configuration.h"
 #include "ocr.h"
 #include "richtext.h"
@@ -238,6 +240,9 @@ HWND control(HWND parent, const wchar_t *cls, const wchar_t *title, DWORD style,
                              scale(parent, width), scale(parent, height), parent, (HMENU)(INT_PTR)id,
                              GetModuleHandleW(nullptr), nullptr);
     SendMessageW(w, WM_SETFONT, (WPARAM)GetPropW(parent, L"Font"), TRUE);
+    if(wcscmp(cls,L"LISTBOX")==0 || wcscmp(cls,WC_LISTVIEWW)==0 ||
+       wcscmp(cls,L"COMBOBOX")==0 || (wcscmp(cls,L"EDIT")==0 && (style&ES_MULTILINE)))
+        enableWheelBatching(w,wcscmp(cls,L"LISTBOX")==0);
     if (auto *layout = windowLayoutState(parent); layout && layout->scrolling)
     {
         layout->controls.push_back({w, {x, y, x + width, y + height}});
@@ -368,11 +373,12 @@ HWND makeWindow(App &app, const wchar_t *cls, const wchar_t *title, WNDPROC proc
     int top = monitor.rcWork.top + std::max(0L, (monitor.rcWork.bottom - monitor.rcWork.top - outerHeight) / 2);
     SetPropW(w, L"WindowLayout", new WindowLayout{width, height, 0, 0, !(extra & WS_THICKFRAME)});
     SetWindowSubclass(w, layoutProc, 2, 0);
+    if(windowLayoutState(w)->scrolling) enableWheelBatching(w);
     RECT initial = fitWindowRect({left, top, left + outerWidth, top + outerHeight}, monitor.rcWork);
     SetWindowPos(w, nullptr, initial.left, initial.top, initial.right - initial.left, initial.bottom - initial.top,
                  SWP_NOACTIVATE | SWP_NOZORDER);
     arrangeWindow(w);
-    SetWindowTextW(w, title);
+    SetWindowTextW(w, localBuildTitle(title).c_str());
     auto smallIcon = (HICON)LoadImageW(app.instance, MAKEINTRESOURCEW(IDI_KSWITCHER), IMAGE_ICON,
                                        GetSystemMetricsForDpi(SM_CXSMICON, dpi),
                                        GetSystemMetricsForDpi(SM_CYSMICON, dpi), LR_SHARED);
@@ -478,7 +484,17 @@ struct HistoryView
     std::map<std::wstring, std::string> richTexts;
     HWND rich{};
     std::set<std::wstring> pending;
+    bool scrolling{};
 };
+bool selectedImage(HWND w, HistoryView *v)
+{
+    int i=(int)SendDlgItemMessageW(w,102,LB_GETCURSEL,0,0);
+    return i>=0 && i<(int)v->items.size() && v->items[i].image;
+}
+void updateHistoryActions(HWND w, HistoryView *v)
+{
+    SetDlgItemTextW(w,114,selectedImage(w,v)?L"Edit image":L"Open item");
+}
 std::wstring selected(HWND w, HistoryView *v)
 {
     int i = (int)SendDlgItemMessageW(w, 102, LB_GETCURSEL, 0, 0);
@@ -507,6 +523,7 @@ void search(HWND w, HistoryView *v)
 }
 void requestPreview(HWND w, HistoryView *v, const Entry &entry)
 {
+    if(v->scrolling) return;
     const auto id = entry.id;
     const bool image = entry.image;
     if (v->thumbnails.contains(id) || v->richTexts.contains(id) || !v->pending.insert(id).second)
@@ -690,6 +707,12 @@ LRESULT CALLBACK historyProc(HWND w, UINT msg, WPARAM wp, LPARAM lp)
     {
         switch (msg)
         {
+        case ScrollActivity:
+            if((HWND)wp==GetDlgItem(w,102)) {
+                v->scrolling=lp!=0;
+                if(!v->scrolling) InvalidateRect((HWND)wp,nullptr,FALSE);
+            }
+            return 0;
         case WM_COMMAND:
         {
             int id = LOWORD(wp);
@@ -702,6 +725,7 @@ LRESULT CALLBACK historyProc(HWND w, UINT msg, WPARAM wp, LPARAM lp)
             }
             if (id == 102 && HIWORD(wp) == LBN_SELCHANGE)
             {
+                updateHistoryActions(w,v);
                 return 0;
             }
             if (id == 102 && HIWORD(wp) == LBN_DBLCLK)
@@ -747,10 +771,13 @@ LRESULT CALLBACK historyProc(HWND w, UINT msg, WPARAM wp, LPARAM lp)
             if (result->generation != v->generation)
                 return 0;
             auto old = selected(w, v);
+            int top=(int)SendDlgItemMessageW(w,102,LB_GETTOPINDEX,0,0);
+            auto topId=top>=0 && top<(int)v->items.size()?v->items[top].id:L"";
             v->items = std::move(result->items);
             SendDlgItemMessageW(w, 102, WM_SETREDRAW, FALSE, 0);
             SendDlgItemMessageW(w, 102, LB_RESETCONTENT, 0, 0);
             int select = 0;
+            int restoreTop=0;
             for (size_t i = 0; i < v->items.size(); ++i)
             {
                 auto &e = v->items[i];
@@ -758,8 +785,11 @@ LRESULT CALLBACK historyProc(HWND w, UINT msg, WPARAM wp, LPARAM lp)
                 SendDlgItemMessageW(w, 102, LB_ADDSTRING, 0, (LPARAM)text.c_str());
                 if (e.id == old)
                     select = (int)i;
+                if(e.id==topId) restoreTop=(int)i;
             }
             SendDlgItemMessageW(w, 102, LB_SETCURSEL, select, 0);
+            SendDlgItemMessageW(w,102,LB_SETTOPINDEX,restoreTop,0);
+            updateHistoryActions(w,v);
             SendDlgItemMessageW(w, 102, WM_SETREDRAW, TRUE, 0);
             InvalidateRect(GetDlgItem(w, 102), nullptr, TRUE);
             return 0;
@@ -770,16 +800,25 @@ LRESULT CALLBACK historyProc(HWND w, UINT msg, WPARAM wp, LPARAM lp)
             if (result->generation != v->generation || !IsWindowVisible(w))
                 return 0;
             v->pending.erase(result->id);
-            // At most ~3.3 MiB, irrespective of history length or source image size.
+            auto list=GetDlgItem(w,102);
-            if (v->thumbnails.size() >= 32)
+            RECT client{}; GetClientRect(list,&client);
-                v->thumbnails.erase(v->thumbnails.begin());
+            std::set<std::wstring> visible;
-            if (v->richTexts.size() >= 32)
+            RECT changed{}; bool repaint=false;
-                v->richTexts.erase(v->richTexts.begin());
+            int top=(int)SendMessageW(list,LB_GETTOPINDEX,0,0);
+            for(int i=std::max(0,top);i<(int)v->items.size();++i) {
+                RECT row{}, intersection{};
+                if(SendMessageW(list,LB_GETITEMRECT,i,(LPARAM)&row)==LB_ERR || row.top>=client.bottom) break;
+                if(!IntersectRect(&intersection,&row,&client)) continue;
+                visible.insert(v->items[i].id);
+                if(v->items[i].id==result->id) { changed=intersection; repaint=true; }
+            }
             if (!result->rtf.empty())
                 v->richTexts[result->id] = std::move(result->rtf);
             else
                 v->thumbnails[result->id] = std::move(result->pixels);
-            InvalidateRect(GetDlgItem(w, 102), nullptr, FALSE);
+            trimHistoryPreviews(v->thumbnails,visible);
+            trimHistoryPreviews(v->richTexts,visible);
+            if(repaint) InvalidateRect(list,&changed,FALSE);
             return 0;
         }
         case WM_MEASUREITEM:
@@ -798,15 +837,29 @@ LRESULT CALLBACK historyProc(HWND w, UINT msg, WPARAM wp, LPARAM lp)
             break;
         case WM_CONTEXTMENU:
         {
+            auto list=GetDlgItem(w,102);
+            if((HWND)wp!=list) break;
+            POINT p{(short)LOWORD(lp),(short)HIWORD(lp)};
+            if(lp!=-1) {
+                POINT hit=p; ScreenToClient(list,&hit);
+                auto item=SendMessageW(list,LB_ITEMFROMPOINT,0,MAKELPARAM(hit.x,hit.y));
+                if(HIWORD(item)) return 0;
+                SendMessageW(list,LB_SETCURSEL,LOWORD(item),0);
+                updateHistoryActions(w,v);
+            } else {
+                RECT row{};
+                auto index=SendMessageW(list,LB_GETCURSEL,0,0);
+                if(index==LB_ERR) return 0;
+                SendMessageW(list,LB_GETITEMRECT,index,(LPARAM)&row);
+                p={row.left,row.top}; ClientToScreen(list,&p);
+            }
             HMENU menu = CreatePopupMenu();
             AppendMenuW(menu, MF_STRING, 110, L"Paste");
             AppendMenuW(menu, MF_STRING, 111, L"Paste plain text");
             AppendMenuW(menu, MF_STRING, 112, L"Pin / unpin");
             AppendMenuW(menu, MF_STRING, 113, L"Delete");
-            AppendMenuW(menu, MF_STRING, 114, L"Open full item");
+            AppendMenuW(menu, MF_STRING, 114, selectedImage(w,v)?L"Edit image in screenshot editor":L"Open full item");
             AppendMenuW(menu, MF_STRING, 115, L"Copy text from image (OCR)");
-            POINT p;
-            GetCursorPos(&p);
             int cmd = TrackPopupMenu(menu, TPM_RETURNCMD, p.x, p.y, 0, w, nullptr);
             DestroyMenu(menu);
             if (cmd)
@@ -1700,11 +1753,17 @@ void showEntry(App &app, const std::wstring &id)
     try
     {
         auto clip = app.history->load(id);
+        if(std::any_of(clip.formats.begin(),clip.formats.end(),[](const auto &format) {
+            return format.id==CF_DIB || format.id==CF_DIBV5 || format.name==L"PNG";
+        })) {
+            launchScreenshotEditor(app,clip);
+            return;
+        }
         auto text = clip.text();
         if (text.empty())
         {
             MessageBoxW(app.historyWindow,
-                        L"This item contains an image or files. Use the preview or paste it into the "
+                        L"This item contains files. Paste it into the "
                         L"destination application.",
                         L"Clipboard item", MB_OK);
             return;

src/ui_scroll.h

@@ -0,0 +1,83 @@
+#pragma once
+#include "platform.h"
+#include <algorithm>
+#include <commctrl.h>
+#include <windowsx.h>
+
+namespace ks {
+inline constexpr UINT ScrollActivity=WM_APP+42;
+inline constexpr UINT_PTR ScrollFrameTimer=0x4b5301, ScrollIdleTimer=0x4b5302;
+struct WheelBatch {
+    long long vertical{}, horizontal{};
+    WORD keys{};
+    LPARAM point{};
+    bool frame{}, active{}, listBox{};
+    int remainder{};
+};
+inline LRESULT CALLBACK wheelBatchProc(HWND w,UINT msg,WPARAM wp,LPARAM lp,UINT_PTR id,DWORD_PTR data)
+{
+    auto *batch=reinterpret_cast<WheelBatch *>(data);
+    if(msg==WM_MOUSEWHEEL || msg==WM_MOUSEHWHEEL) {
+        (msg==WM_MOUSEWHEEL?batch->vertical:batch->horizontal)+=GET_WHEEL_DELTA_WPARAM(wp);
+        batch->keys=GET_KEYSTATE_WPARAM(wp); batch->point=lp;
+        if(!batch->active) {
+            batch->active=true;
+            SendMessageW(GetParent(w),ScrollActivity,(WPARAM)w,TRUE);
+        }
+        // Do not restart the frame timer: an uninterrupted wheel stream must
+        // keep moving, rather than wait for a debounce interval to expire.
+        if(!batch->frame) batch->frame=SetTimer(w,ScrollFrameTimer,16,nullptr)!=0;
+        SetTimer(w,ScrollIdleTimer,100,nullptr);
+        return 0;
+    }
+    if(msg==WM_TIMER && wp==ScrollFrameTimer) {
+        KillTimer(w,ScrollFrameTimer); batch->frame=false;
+        if(batch->listBox && batch->vertical) {
+            UINT lines=3; SystemParametersInfoW(SPI_GETWHEELSCROLLLINES,0,&lines,0);
+            if(lines==WHEEL_PAGESCROLL) {
+                RECT client{}; GetClientRect(w,&client);
+                auto height=SendMessageW(w,LB_GETITEMHEIGHT,0,0);
+                lines=std::max<LRESULT>(1,client.bottom/std::max<LRESULT>(1,height));
+            }
+            auto delta=batch->vertical+batch->remainder;
+            batch->remainder=(int)(delta%WHEEL_DELTA);
+            auto top=SendMessageW(w,LB_GETTOPINDEX,0,0);
+            auto count=SendMessageW(w,LB_GETCOUNT,0,0);
+            auto next=std::clamp<long long>(top-(delta/WHEEL_DELTA)*lines,0,std::max<LRESULT>(0,count-1));
+            if(next!=top) SendMessageW(w,LB_SETTOPINDEX,(WPARAM)next,0);
+            batch->vertical=0;
+        } else if(batch->vertical) {
+            // Native edit/list-view/window handlers retain their own scrolling
+            // semantics, including system settings and partial wheel deltas.
+            auto delta=(short)std::clamp<long long>(batch->vertical,-32760,32760);
+            batch->vertical-=delta;
+            DefSubclassProc(w,WM_MOUSEWHEEL,MAKEWPARAM(batch->keys,(WORD)delta),batch->point);
+        }
+        if(batch->horizontal) {
+            auto delta=(short)std::clamp<long long>(batch->horizontal,-32760,32760);
+            batch->horizontal-=delta;
+            DefSubclassProc(w,WM_MOUSEHWHEEL,MAKEWPARAM(batch->keys,(WORD)delta),batch->point);
+        }
+        if(batch->vertical || batch->horizontal)
+            batch->frame=SetTimer(w,ScrollFrameTimer,16,nullptr)!=0;
+        return 0;
+    }
+    if(msg==WM_TIMER && wp==ScrollIdleTimer) {
+        if(batch->frame) return 0;
+        KillTimer(w,ScrollIdleTimer); batch->active=false;
+        SendMessageW(GetParent(w),ScrollActivity,(WPARAM)w,FALSE);
+        return 0;
+    }
+    if(msg==WM_NCDESTROY) {
+        KillTimer(w,ScrollFrameTimer); KillTimer(w,ScrollIdleTimer);
+        RemoveWindowSubclass(w,wheelBatchProc,id); delete batch;
+    }
+    return DefSubclassProc(w,msg,wp,lp);
+}
+inline void enableWheelBatching(HWND window,bool listBox=false)
+{
+    if(!window) return;
+    auto *batch=new WheelBatch; batch->listBox=listBox;
+    if(!SetWindowSubclass(window,wheelBatchProc,ScrollFrameTimer,(DWORD_PTR)batch)) delete batch;
+}
+}

src/update.h

@@ -2,7 +2,7 @@
 #include "platform.h"
 namespace ks
 {
-inline constexpr wchar_t AppVersion[] = L"0.6.18";
+inline constexpr wchar_t AppVersion[] = L"0.6.20";
 inline constexpr UINT UpdateMessage = WM_APP + 7;
 inline constexpr UINT UpdateCheckIntervalMs = 6 * 60 * 60 * 1000;
 inline constexpr UINT UpdateNotificationRetryMs = 5 * 60 * 1000;

tests/input.cpp

@@ -1,4 +1,5 @@
 #include "app.h"
+#include "ui_scroll.h"
 #include "ui_geometry.h"
 #include "screenshot.h"
 #include <commctrl.h>
@@ -728,16 +729,21 @@ int main(int argc, char **argv) {
             controlMoves=0;
             ValidateRect(settings,nullptr);
             SendMessageW(settings,WM_MOUSEWHEEL,MAKEWPARAM(0,WHEEL_DELTA),0);
+            SendMessageW(settings,WM_TIMER,ks::ScrollFrameTimer,0);
             require(controlMoves==0 && !GetUpdateRect(settings,nullptr,FALSE),"wheel at top does not move controls or erase the window");
             SendMessageW(settings,WM_MOUSEWHEEL,MAKEWPARAM(0,WORD(short(-WHEEL_DELTA/2))),0);
+            SendMessageW(settings,WM_TIMER,ks::ScrollFrameTimer,0);
             require(controlMoves==0,"partial wheel step does not rearrange controls");
             SendMessageW(settings,WM_MOUSEWHEEL,MAKEWPARAM(0,WORD(short(-WHEEL_DELTA/2))),0);
+            require(controlMoves==0,"wheel changes wait for the shared frame timer");
+            SendMessageW(settings,WM_TIMER,ks::ScrollFrameTimer,0);
             require(controlMoves==1,"wheel scroll batches each control movement once");
             SendMessageW(settings,WM_VSCROLL,SB_BOTTOM,0);
             SendMessageW(settings,WM_HSCROLL,SB_RIGHT,0);
             controlMoves=0;
             SendMessageW(settings,WM_MOUSEWHEEL,MAKEWPARAM(0,-WHEEL_DELTA),0);
             SendMessageW(settings,WM_MOUSEHWHEEL,MAKEWPARAM(0,WHEEL_DELTA),0);
+            SendMessageW(settings,WM_TIMER,ks::ScrollFrameTimer,0);
             require(controlMoves==0,"wheel at bottom and right boundaries does not rearrange controls");
             require((GetWindowLongPtrW(settings,GWL_STYLE)&WS_CLIPCHILDREN)!=0,"parent background excludes child controls");
             RemoveWindowSubclass(trackedControl,countControlMoves,99);

tests/integration.cpp

@@ -25,8 +25,51 @@ bool captured = false, failed = false;
 bool conversionOnly = false;
 int pasteBehavior = 0;
 int enterPresses = 0;
+int copyFailuresRemaining = 0, copyRequests = 0;
+bool temporaryClipboardExcluded = true;
+bool clipboardAccessTimedOut = false;
 LRESULT CALLBACK observeEnter(HWND w, UINT message, WPARAM wp, LPARAM lp, UINT_PTR, DWORD_PTR)
 {
+    // This bare EDIT control is our test fixture, not a full editor with
+    // clipboard retries. Keep clipboard access on its owning UI thread while
+    // it handles Ctrl+C/Ctrl+V, so unrelated Windows clipboard listeners cannot
+    // make the fixture silently discard the operation under test.
+    struct ClipboardAccess
+    {
+        bool opened = false;
+        ~ClipboardAccess() { if (opened) CloseClipboard(); }
+    } access;
+    if (message == WM_CHAR && (wp == 3 || wp == 22))
+    {
+        auto deadline = GetTickCount64() + 1000;
+        do
+        {
+            if (OpenClipboard(w)) { access.opened = true; break; }
+            Sleep(10);
+        } while (GetTickCount64() < deadline);
+        if (!access.opened)
+        {
+            clipboardAccessTimedOut = true;
+            return 0;
+        }
+    }
+    if ((message == WM_CHAR && wp == 3) || message == WM_PASTE)
+    {
+        temporaryClipboardExcluded &= IsClipboardFormatAvailable(
+            RegisterClipboardFormatW(L"ExcludeClipboardContentFromMonitorProcessing")) != FALSE;
+        if (message == WM_CHAR)
+        {
+            ++copyRequests;
+            // Native EDIT silently ignores Ctrl+C when OpenClipboard fails.
+            // Reproduce that outcome deterministically, without depending on
+            // the timing of the Windows clipboard-history service.
+            if (copyFailuresRemaining > 0)
+            {
+                --copyFailuresRemaining;
+                return 0;
+            }
+        }
+    }
     if (message == WM_PASTE && pasteBehavior)
     {
         if (pasteBehavior == 2) SendMessageW(w, EM_REPLACESEL, TRUE, (LPARAM)L"other!");
@@ -51,13 +94,15 @@ std::string diagnosticLog()
 size_t diagnosticStart{};
 void require(bool ok, const char *name)
 {
-    if (!ok)
+    if (!ok || clipboardAccessTimedOut)
     {
         wchar_t observed[2048]{};
         GetWindowTextW(field, observed, 2048);
         std::cerr << "Editor at failure: " << ks::utf8(observed)
                   << "; foregroundSame=" << (GetForegroundWindow() == host)
                   << "; inputVersion=" << app->inputVersion.load() << '\n';
+        if (clipboardAccessTimedOut)
+            throw std::runtime_error("Test editor could not acquire clipboard within 1000 ms");
         throw std::runtime_error(name);
     }
     std::cout << "PASS " << name << '\n';
@@ -109,6 +154,9 @@ LRESULT CALLBACK procedure(HWND w, UINT msg, WPARAM wp, LPARAM lp)
         return 0;
     if (msg == WM_TIMER)
     {
+        // Input tests must not start a network update check. Its close veto can
+        // otherwise leave a completed test running after the editor is gone.
+        if (app->window) KillTimer(app->window, 5);
         try
         {
             if (GetTickCount64() > deadline)
@@ -257,6 +305,7 @@ LRESULT CALLBACK procedure(HWND w, UINT msg, WPARAM wp, LPARAM lp)
                 DestroyWindow(field);
                 field = CreateWindowW(L"EDIT", L"", WS_CHILD | WS_VISIBLE | WS_BORDER | ES_PASSWORD, 20, 20,
                                       590, 30, host, nullptr, GetModuleHandleW(nullptr), nullptr);
+                SetWindowSubclass(field, observeEnter, 1, 0);
                 prepare(L"ghbdtn ", false);
                 record(L"ghbdtn ");
                 app->transform(ks::AutoCorrect);
@@ -268,6 +317,7 @@ LRESULT CALLBACK procedure(HWND w, UINT msg, WPARAM wp, LPARAM lp)
                 DestroyWindow(field);
                 field = CreateWindowW(L"EDIT", L"", WS_CHILD | WS_VISIBLE | WS_BORDER, 20, 20, 590, 30, host,
                                       nullptr, GetModuleHandleW(nullptr), nullptr);
+                SetWindowSubclass(field, observeEnter, 1, 0);
                 prepare(L"(ljvf ", false);
                 record(L"(ljvf ");
                 app->transform(ks::AutoCorrect);
@@ -347,6 +397,18 @@ LRESULT CALLBACK procedure(HWND w, UINT msg, WPARAM wp, LPARAM lp)
             case 30:
             case 32:
             case 34:
+            case 37:
+                // Earlier password/word tests replace the original multiline
+                // editor with a single-line EDIT. Restore the snippet fixture:
+                // a single-line control cannot insert the tested Enter action.
+                if (!(GetWindowLongPtrW(field, GWL_STYLE) & ES_MULTILINE))
+                {
+                    DestroyWindow(field);
+                    field = CreateWindowW(L"EDIT", L"", WS_CHILD | WS_VISIBLE | WS_BORDER |
+                        ES_MULTILINE | ES_WANTRETURN, 20, 20, 590, 230, host, nullptr,
+                        GetModuleHandleW(nullptr), nullptr);
+                    SetWindowSubclass(field, observeEnter, 1, 0);
+                }
                 if (!captured)
                 {
                     saved = ks::readClipboard(app->window, 64 * 1024 * 1024);
@@ -355,9 +417,16 @@ LRESULT CALLBACK procedure(HWND w, UINT msg, WPARAM wp, LPARAM lp)
                 app->ownSequence = ks::writeClipboard(app->window, ks::textClip(sentinel));
                 app->settings.autoCorrect = stage == 35;
                 app->settings.autoLanguages = {L"en", L"ru"};
+                app->settings.cycle = {app->layouts[en].id, app->layouts[ru].id};
+                app->settings.switchLayout = false;
+                app->autoCorrector = ks::AutoCorrector{};
+                app->autoPredictor = ks::AutoCorrector{};
                 app->autoPredictor.configure(L"dictionaries", app->settings.autoLanguages);
                 app->settings.snippets = {{L";r", stage == 31 ? L"rider .{cursor}" : L"rider .{cursor}{enter}"}};
                 enterPresses = 0;
+                copyRequests = 0;
+                copyFailuresRemaining = stage == 38 ? 10 : stage == 33 ? 1 : 0;
+                temporaryClipboardExcluded = true;
                 ActivateKeyboardLayout(app->layouts[en].handle, 0);
                 prepare(L"prefix ", false);
                 {
@@ -384,6 +453,10 @@ LRESULT CALLBACK procedure(HWND w, UINT msg, WPARAM wp, LPARAM lp)
                 break;
             case 33:
                 require(text() == L"prefix rider .\r\n x", "Enter action precedes buffered typing");
+                require(copyRequests == 2 && copyFailuresRemaining == 0,
+                        "snippet retries a silently dropped copy without duplicating input");
+                require(temporaryClipboardExcluded,
+                        "temporary snippet clipboard contents are excluded from Windows history");
                 require(enterPresses == 1, "Enter marker sends an actual Enter key press");
                 require(ks::readClipboard(app->window).text() == sentinel, "Enter snippet restores clipboard");
                 stage = 34;
@@ -407,6 +480,15 @@ LRESULT CALLBACK procedure(HWND w, UINT msg, WPARAM wp, LPARAM lp)
                 break;
             case 36:
                 require(text() == L"prefix rider .\r\nghbdtn привет ", "automatic correction resumes for subsequent normal typing");
+                stage = 37;
+                break;
+            case 38:
+                require(copyRequests == 3, "copy retries are bounded to three attempts");
+                require(text() == L"prefix ;r x" && enterPresses == 0,
+                        "exhausted copy retries preserve trigger and following input without Enter");
+                require(ks::readClipboard(app->window).text() == sentinel,
+                        "exhausted copy retries restore the clipboard");
+                copyFailuresRemaining = 0;
                 finish();
                 break;
             case 20:

tests/screenshot_ui.cpp

@@ -175,7 +175,7 @@ int main()
         }
         c.marks.clear(); SendMessageW(window,WM_COMMAND,27,0);
         wchar_t windowTitle[128]{}; GetWindowTextW(window,windowTitle,128);
-        require(std::wstring(windowTitle)==L"KSwitcher — Screenshot #1","title includes editor index without usage hints");
+        require(std::wstring(windowTitle)==ks::localBuildTitle(L"KSwitcher — Screenshot #1"),"title includes editor index and local build marker without usage hints");
         RECT client{}; GetClientRect(window,&client);
         require(c.view.bottom<=client.bottom-c.statusHeight,"image does not overlap status bar");
         ks::updateStatus(c);

tests/scroll.cpp

@@ -0,0 +1,66 @@
+#include "ui_scroll.h"
+#include <iostream>
+
+namespace {
+int forwarded{};
+long long totalDelta{};
+LRESULT CALLBACK observe(HWND w,UINT msg,WPARAM wp,LPARAM lp,UINT_PTR,DWORD_PTR)
+{
+    if(msg==WM_MOUSEWHEEL) { ++forwarded; totalDelta+=GET_WHEEL_DELTA_WPARAM(wp); }
+    return DefSubclassProc(w,msg,wp,lp);
+}
+void require(bool ok,const char *message) { if(!ok) throw std::runtime_error(message); }
+void wheel(HWND w,int delta) { SendMessageW(w,WM_MOUSEWHEEL,MAKEWPARAM(0,(WORD)(short)delta),0); }
+void flush(HWND w) { SendMessageW(w,WM_TIMER,ks::ScrollFrameTimer,0); }
+}
+int main()
+{
+    INITCOMMONCONTROLSEX init{sizeof(init),ICC_STANDARD_CLASSES|ICC_LISTVIEW_CLASSES};
+    InitCommonControlsEx(&init);
+    auto instance=GetModuleHandleW(nullptr);
+    auto parent=CreateWindowW(L"STATIC",L"Scroll regression",WS_OVERLAPPEDWINDOW,0,0,500,400,nullptr,nullptr,instance,nullptr);
+    try {
+        auto list=CreateWindowW(L"LISTBOX",L"",WS_CHILD|WS_VSCROLL,0,0,300,200,parent,nullptr,instance,nullptr);
+        for(int i=0;i<2000;++i) SendMessageW(list,LB_ADDSTRING,0,(LPARAM)L"row");
+        SendMessageW(list,LB_SETCURSEL,5,0);
+        SendMessageW(list,LB_SETTOPINDEX,0,0);
+        ks::enableWheelBatching(list,true);
+        for(int i=0;i<1000;++i) wheel(list,-120);
+        require(SendMessageW(list,LB_GETTOPINDEX,0,0)==0,"burst is deferred to one frame");
+        flush(list);
+        UINT lines{}; SystemParametersInfoW(SPI_GETWHEELSCROLLLINES,0,&lines,0);
+        require(!lines || SendMessageW(list,LB_GETTOPINDEX,0,0)>0,"burst moves list");
+        require(SendMessageW(list,LB_GETCURSEL,0,0)==5,"scroll does not change selection");
+        for(int i=0;i<1000;++i) wheel(list,120);
+        flush(list);
+        require(SendMessageW(list,LB_GETTOPINDEX,0,0)==0,"reverse burst clamps at top");
+        wheel(list,-60); flush(list);
+        require(SendMessageW(list,LB_GETTOPINDEX,0,0)==0,"partial wheel step is retained");
+        wheel(list,-60); flush(list);
+        require(!lines || SendMessageW(list,LB_GETTOPINDEX,0,0)>0,"partial steps combine across frames");
+        DestroyWindow(list);
+        for(auto cls:{L"EDIT",WC_LISTVIEWW,L"COMBOBOX",L"STATIC"}) {
+            auto w=CreateWindowW(cls,L"",WS_CHILD|WS_VSCROLL,0,0,300,200,parent,nullptr,instance,nullptr);
+            require(w!=nullptr,"native scroll control created");
+            SetWindowSubclass(w,observe,1,0); ks::enableWheelBatching(w);
+            forwarded=0; totalDelta=0;
+            for(int i=0;i<100;++i) wheel(w,-120);
+            require(forwarded==0,"native wheel burst is batched");
+            flush(w);
+            require(forwarded==1 && totalDelta==-12000,"one native dispatch preserves burst distance");
+            wheel(w,60); flush(w);
+            require(forwarded==2 && totalDelta==-11940,"native partial steps are preserved");
+            forwarded=0; totalDelta=0;
+            for(int i=0;i<400;++i) wheel(w,-120);
+            flush(w); flush(w);
+            require(forwarded==2 && totalDelta==-48000,"large native burst is not truncated to 16 bits");
+            SendMessageW(w,WM_TIMER,ks::ScrollIdleTimer,0);
+            DestroyWindow(w);
+        }
+        DestroyWindow(parent);
+        std::cout<<"Passed shared wheel batching regressions (list, edit, table, combo, window)\n";
+        return 0;
+    } catch(const std::exception &e) {
+        DestroyWindow(parent); std::cerr<<e.what()<<'\n'; return 1;
+    }
+}

tests/tests.cpp

@@ -1,4 +1,5 @@
 #include "autocorrect.h"
+#include "history_preview.h"
 #include "ocr.h"
 #include "richtext.h"
 #include "storage.h"
@@ -22,6 +23,20 @@ void rejects(const std::function<void()> &f, const char *name)
     bool thrown = false;
     try
     {
+        {
+            std::map<std::wstring,int> previews;
+            std::set<std::wstring> visible;
+            for(int i=0;i<40;++i) previews[std::to_wstring(i)]=i;
+            for(int i=0;i<8;++i) visible.insert(std::to_wstring(i));
+            ks::trimHistoryPreviews(previews,visible);
+            require(previews.size()==32,"preview cache stays bounded");
+            for(const auto &id:visible) require(previews.contains(id),"visible preview survives eviction");
+            for(int i=0;i<40;++i) { auto id=std::to_wstring(i); previews[id]=i; visible.insert(id); }
+            ks::trimHistoryPreviews(previews,visible);
+            require(previews.size()==40,"tall viewport does not thrash visible previews");
+            visible.clear(); ks::trimHistoryPreviews(previews,visible);
+            require(previews.size()==32,"cache shrinks after leaving tall viewport");
+        }
         f();
     }
     catch (...)