diff --git a/private/lib/windows/x86_64/rktwebview.dll b/private/lib/windows/x86_64/rktwebview.dll
new file mode 100644
index 0000000..21a44db
Binary files /dev/null and b/private/lib/windows/x86_64/rktwebview.dll differ
diff --git a/private/lib/windows/x86_64/rktwebview_prg.exe b/private/lib/windows/x86_64/rktwebview_prg.exe
new file mode 100644
index 0000000..9ac1f7b
Binary files /dev/null and b/private/lib/windows/x86_64/rktwebview_prg.exe differ
diff --git a/private/lib/windows/x86_64/rktwebview_qt.dll b/private/lib/windows/x86_64/rktwebview_qt.dll
deleted file mode 100644
index 8676948..0000000
Binary files a/private/lib/windows/x86_64/rktwebview_qt.dll and /dev/null differ
diff --git a/private/lib/windows/x86_64/rktwebview_qt_test.exe b/private/lib/windows/x86_64/rktwebview_qt_test.exe
deleted file mode 100644
index 0337098..0000000
Binary files a/private/lib/windows/x86_64/rktwebview_qt_test.exe and /dev/null differ
diff --git a/private/lib/windows/x86_64/rktwebview_test.exe b/private/lib/windows/x86_64/rktwebview_test.exe
new file mode 100644
index 0000000..2a1ab41
Binary files /dev/null and b/private/lib/windows/x86_64/rktwebview_test.exe differ
diff --git a/private/racket-webview-qt.rkt b/private/racket-webview-qt.rkt
index ad997fb..be8fbc2 100644
--- a/private/racket-webview-qt.rkt
+++ b/private/racket-webview-qt.rkt
@@ -142,7 +142,12 @@
         (putenv "QTWEBENGINE_LOCALES_PATH"
                 (path->string (build-path os-lib-dir "translations" "qtwebengine_locales")))
         (putenv "RKT_WEBVIEW_PRG"
+                (let ((p 
                 (path->string (build-path os-lib-dir rktwebview-prg)))
+                      )
+                  (displayln p)
+                  p
+                  ))
         (when (eq? os 'linux)
           (putenv "QT_QPA_PLATFORM" "xcb")
           (putenv "LD_LIBRARY_PATH"
@@ -222,8 +227,19 @@
            eval_js_failed = 3
            no_devtools_on_platform = 4
            no_delegate_for_context = 5
+           webview_missing_dependency = 6 
+           webview_canceled = 7
+           webview_invalid_state = 8
+           webview_invalid_argument = 9
+           webview_unspecified = 10
+           webview_dispatch_failed = 11
            move_failed = 12
            resize_failed = 13
+           choose_dir_failed = 14
+           open_file_failed = 15
+           save_file_failed = 16
+           failed = 17
+           invalid_handle = 18
            )
          )
   )
diff --git a/rktwebview_qt/CMakeLists.txt b/rktwebview_qt/CMakeLists.txt
index 26adecf..48bc0b1 100644
--- a/rktwebview_qt/CMakeLists.txt
+++ b/rktwebview_qt/CMakeLists.txt
@@ -21,6 +21,7 @@ add_library(rktwebview SHARED
   rkt_protocol.h
   rktwebview_types.h
   json.cpp json.h
+  utils.h
 )
 
 add_executable(rktwebview_prg
diff --git a/rktwebview_qt/main.cpp b/rktwebview_qt/main.cpp
index 1b96cc4..ebf7a7c 100644
--- a/rktwebview_qt/main.cpp
+++ b/rktwebview_qt/main.cpp
@@ -62,8 +62,10 @@ int main(int argc, char *argv[])
 {
     const char *me = argv[0];
 
+    fprintf(stderr, "%s runs\n", argv[0]);fflush(stderr);
+
     if (argc < 6) {
-        fprintf(stderr, "%s: wrong number of arguments\n", me);
+        fprintf(stderr, "%s: wrong number of arguments\n", me);fflush(stderr);
         exit(1);
     }
 
@@ -78,11 +80,11 @@ int main(int argc, char *argv[])
     int res_slot = atoi(res_slot_str);
     int evt_slot = atoi(evt_slot_str);
 
-    fprintf(stderr, "%s %s %s %s %s %s\n", me, shm_name, shm_size_str, cmd_slot_str, res_slot_str, evt_slot_str);
-    fprintf(stderr, "%s %s %ld %d %d %d\n", me, shm_name, shm_size, cmd_slot, res_slot, evt_slot);
+    fprintf(stderr, "%s %s %s %s %s %s\n", me, shm_name, shm_size_str, cmd_slot_str, res_slot_str, evt_slot_str);fflush(stderr);
+    fprintf(stderr, "%s %s %ld %d %d %d\n", me, shm_name, shm_size, cmd_slot, res_slot, evt_slot);fflush(stderr);
 
     if (!(shm_size > 0 && cmd_slot > 0 && res_slot > 0 && evt_slot > 0)) {
-        fprintf(stderr, "%s: Invalid shm size or slots\n", me);
+        fprintf(stderr, "%s: Invalid shm size or slots\n", me);fflush(stderr);
         exit(2);
     }
 
@@ -98,10 +100,10 @@ int main(int argc, char *argv[])
     handler->webview_handler->initApp();
     handler->webview_handler->execApp();
 
-    fprintf(stderr, "waiting for thread to end\n");
+    fprintf(stderr, "waiting for thread to end\n");fflush(stderr);
     handler->wait();
 
-    fprintf(stderr, "cleaning up shm\n");
+    fprintf(stderr, "cleaning up shm\n");fflush(stderr);
 
     delete handler->webview_handler;
     delete handler->command_queue;
@@ -318,7 +320,7 @@ void Handler::run()
             }
             break;
             default: {
-                fprintf(stderr, "Unknown command: %d\n", cmd);
+                fprintf(stderr, "Unknown command: %d\n", cmd);fflush(stderr);
             }
         }
     }
diff --git a/rktwebview_qt/rktwebview.cpp b/rktwebview_qt/rktwebview.cpp
index 3e6d10a..3bba070 100644
--- a/rktwebview_qt/rktwebview.cpp
+++ b/rktwebview_qt/rktwebview.cpp
@@ -2,13 +2,19 @@
 #include <chrono>
 #include <stdint.h>
 #include <string.h>
+#ifdef _WIN32
+#include <windows.h>
+#include <filesystem>
+#else
 #include <unistd.h>
+#include <spawn.h>
+#endif
 #include <fcntl.h>
 #include "rktwebview.h"
 #include "rkt_protocol.h"
-#include <spawn.h>
 #include "shmqueue.h"
 #include "json.h"
+#include "utils.h"
 
 #define SHM_SIZE (10 * 1024 * 1024)     // 10MB
 #define COMMAND_SLOT        1
@@ -28,14 +34,26 @@ typedef struct {
     ShmQueue *command_queue;
     ShmQueue *command_result_queue;
     ShmQueue *event_queue;
+#ifdef _WIN32
+    HANDLE rkt_webview_prg_pid;
+#else
     pid_t rkt_webview_prg_pid;
+#endif
+
     bool rkt_webview_prg_started;
+    bool valid;
 } Handle_t;
 
 Handle_t *handler = nullptr;
 
 static bool fileExists(const char *filename) {
+#ifdef _WIN32
+    DWORD dwAttrib = GetFileAttributes(filename);
+    return (dwAttrib != INVALID_FILE_ATTRIBUTES &&
+            !(dwAttrib & FILE_ATTRIBUTE_DIRECTORY));
+#else
     return access(filename, X_OK) != -1;
+#endif
 }
 
 uint64_t current_ms() {
@@ -45,29 +63,62 @@ uint64_t current_ms() {
 
 bool runRktWebview(Handle_t *handler)
 {
-    // run rktwebview_prg using the environment variable RKT_WEBVIEW_PRG
-#ifdef _WIN32
-#else
     char *rkt_webview_prg_path = getenv("RKT_WEBVIEW_PRG");
     if (rkt_webview_prg_path == nullptr) {
-        fprintf(stderr, "RKT_WEBVIEW_PRG environment variable not set, cannot start webview program\n");
+        fprintf(stderr, "RKT_WEBVIEW_PRG environment variable not set, cannot start webview program\n");fflush(stderr);
         return false;
     }
     if (!fileExists(rkt_webview_prg_path)) {
-        fprintf(stderr, "%s does not exist or is not executable\n", rkt_webview_prg_path);
+        fprintf(stderr, "%s does not exist or is not executable\n", rkt_webview_prg_path);fflush(stderr);
         return false;
     }
 
+    std::string path = basedir(rkt_webview_prg_path);
+
     char shm_size_str[30];
     char command_slot[10];
     char command_result_slot[10];
     char event_slot[10];
 
-    sprintf(shm_size_str, "%ld", handler->shm_size);
+    sprintf(shm_size_str, "%d", static_cast<int>(handler->shm_size));
     sprintf(command_slot, "%d", COMMAND_SLOT);
     sprintf(command_result_slot, "%d", COMMAND_RESULT_SLOT);
     sprintf(event_slot, "%d", EVENT_SLOT);
 
+    // run rktwebview_prg using the environment variable RKT_WEBVIEW_PRG
+#ifdef _WIN32
+
+    //STARTUPINFO si;
+    //PROCESS_INFORMATION pi;
+    //ZeroMemory( &si, sizeof(si) );
+    //si.cb = sizeof(si);
+    //ZeroMemory( &pi, sizeof(pi) );
+
+    std::string cmdargs = std::string("") + handler->name + " " + shm_size_str + " " + command_slot + " " + command_result_slot + " " + event_slot;
+    std::string exe = std::string(rkt_webview_prg_path);
+
+    const char *td = getenv("TEMP");
+    if (td == nullptr) { td = "C:\\"; }
+    std::string tmpdir = td;
+    std::string logfile = tmpdir + "\\" + "rktwebview.log"; //handler->name + ".log";
+    std::string errfile = tmpdir + "\\" + "rktwebview.err";
+    std::string redirect = " ^>" + logfile + " 2^>" + errfile;
+    std::string cmdline = "start /b \"\" cmd /c \"" + exe + " " + cmdargs + " " + /*redirect*/ + "\"" + redirect;
+
+    char *cmdline_str = const_cast<char *>(cmdline.c_str());
+
+    auto cwd = std::filesystem::current_path();
+    std::filesystem::current_path(path);
+    int r = system(cmdline_str);
+    std::filesystem::current_path(cwd);
+
+        //CreateProcessA(NULL, cmdline_str, NULL, NULL, FALSE, NORMAL_PRIORITY_CLASS, NULL, path.c_str(), &si, &pi);
+    handler->rkt_webview_prg_pid = 0;
+    if (r != 0) {
+        fprintf(stderr, "Cannot create process '%s' (error = %ld)\n", cmdline_str, GetLastError());fflush(stderr);
+    }
+    return (r == 0);
+#else
     char *argv[] = { rkt_webview_prg_path, const_cast<char *>(handler->name.c_str()), shm_size_str, command_slot, command_result_slot, event_slot, nullptr };
 
     int r = posix_spawn(&handler->rkt_webview_prg_pid, rkt_webview_prg_path, nullptr, nullptr, argv, environ);
@@ -108,18 +159,21 @@ void rkt_webview_cleanup()
             handler = nullptr;
         }
         */
-        fprintf(stderr, "Sending quit message\n");
-        handler->command_queue->enqueue(CMD_QUIT);
-        fprintf(stderr, "Message sent\n");
-        bool stopped = false;
-        while(!stopped) {
-            int cmd;
-            std::string s;
-            fprintf(stderr, "Getting result of quit message\n");
-            handler->command_result_queue->dequeue(cmd, s, true);
-            fprintf(stderr, "got %d\n", cmd);
-            if (cmd == RESULT_QUIT) {
-                stopped = true;
+
+        if (handler->valid) {
+            fprintf(stderr, "Sending quit message\n");fflush(stderr);
+            handler->command_queue->enqueue(CMD_QUIT);
+            fprintf(stderr, "Message sent\n");fflush(stderr);
+            bool stopped = false;
+            while(!stopped) {
+                int cmd;
+                std::string s;
+                fprintf(stderr, "Getting result of quit message\n");fflush(stderr);
+                handler->command_result_queue->dequeue(cmd, s, true);
+                fprintf(stderr, "got %d\n", cmd);fflush(stderr);
+                if (cmd == RESULT_QUIT) {
+                    stopped = true;
+                }
             }
         }
 
@@ -140,16 +194,23 @@ void rkt_webview_init()
         char buf[1024];
 #ifdef DEBUG
         sprintf(buf, "rktwebview-dbg");
+#else
+#ifdef _WIN32
+        DWORD p = GetCurrentProcessId();
+        sprintf(buf, "rktwebview-%ld", p);
 #else
         pid_t p = getpid();
         sprintf(buf, "rktwebview-%x", p);
+#endif
 #endif
 
         handler = new Handle_t;
+        handler->valid = true;
         handler->name = buf;
 
         handler->shm_size = SHM_SIZE;
         handler->shm = new Shm(handler->name.data(), handler->shm_size, true);
+        if (!handler->shm->isValid()) { handler->valid = false; }
         handler->command_queue = new ShmQueue(handler->shm, COMMAND_SLOT, true);
         handler->command_result_queue = new ShmQueue(handler->shm, COMMAND_RESULT_SLOT, true);
         handler->event_queue = new ShmQueue(handler->shm, EVENT_SLOT, true);
@@ -157,6 +218,7 @@ void rkt_webview_init()
         // Start rktwebview_prg application with the right information
 #ifndef DEBUG
         handler->rkt_webview_prg_started = runRktWebview(handler);
+        if (!handler->rkt_webview_prg_started) { handler->valid = false; }
 #endif
     }
 }
@@ -164,7 +226,7 @@ void rkt_webview_init()
 bool rkt_webview_valid(rktwebview_t wv)
 {
     rkt_webview_init();
-    if (handler != nullptr && handler->rkt_webview_prg_started) {
+    if (handler != nullptr && handler->valid) {
         handler->command_queue->enqueue(CMD_HANDLE_IS_VALID);
         int result;
         std::string json_result;
@@ -175,9 +237,21 @@ bool rkt_webview_valid(rktwebview_t wv)
     }
 }
 
+static inline bool validHandle()
+{
+    return (handler != nullptr) && handler->valid;
+}
+
+#define FAIL_HANDLE if (!validHandle()) { return result_t::invalid_handle; }
+#define FAIL_CONTEXT if (!validHandle()) { return 0; }
+#define FAIL_WV if (!validHandle()) { return 0; }
+#define NOOP_HANDLE if (!validHandle()) { return; }
+#define FAIL_CALL_JS if (!validHandle()) { return nullptr; }
+
 rkt_wv_context_t rkt_webview_new_context(const char *boilerplate_js, const char *optional_server_cert_pem)
 {
     rkt_webview_init();
+    FAIL_CONTEXT
 
     JSON j;
 
@@ -200,6 +274,8 @@ rkt_wv_context_t rkt_webview_new_context(const char *boilerplate_js, const char
 int rkt_webview_create(rkt_wv_context_t context, rktwebview_t parent)
 {
     rkt_webview_init();
+    FAIL_WV
+
     JSON j;
     j["context"] = context;
     j["parent"] = parent;
@@ -216,6 +292,7 @@ int rkt_webview_create(rkt_wv_context_t context, rktwebview_t parent)
 void rkt_webview_close(rktwebview_t wv)
 {
     rkt_webview_init();
+    NOOP_HANDLE
 
     JSON j;
     j["wv"] = wv;
@@ -224,6 +301,7 @@ void rkt_webview_close(rktwebview_t wv)
 
 #define CMDRES4(cmd, wv, key, val, key2, val2, key3, val3, key4, val4) \
     rkt_webview_init(); \
+    FAIL_HANDLE \
     JSON j; \
     j["wv"] = wv; \
     j[key] = val; \
@@ -268,6 +346,7 @@ result_t rkt_webview_run_js(rktwebview_t wv, const char *js)
 rkt_data_t *rkt_webview_call_js(rktwebview_t wv, const char *js)
 {
     rkt_webview_init();
+    FAIL_CALL_JS
 
     JSON j;
     j["wv"] = wv;
@@ -380,6 +459,7 @@ result_t rkt_webview_file_save(rktwebview_t w, const char *title, const char *ba
 void rkt_webview_set_ou_token(rktwebview_t wv, const char *token)
 {
     rkt_webview_init();
+    NOOP_HANDLE
 
     JSON j;
     j["wv"] = wv;
@@ -401,7 +481,7 @@ void rkt_webview_free_data(rkt_data_t *d)
         free(d->data.js_result.value);
         free(d);
     } else {
-        fprintf(stderr, "UNEXPECTED: data kind %d cannot be freed\n", d->kind);
+        fprintf(stderr, "UNEXPECTED: data kind %d cannot be freed\n", d->kind);fflush(stderr);
     }
 }
 
@@ -440,7 +520,7 @@ rkt_data_t *rkt_webview_get_event()
         memcpy(d->data.event.event, data.c_str(), ds);
         d->data.event.event[ds] = '\0';
         d->data.event.wv = wv;
-        fprintf(stderr, "event: %d - '%s'\n", d->data.event.wv, d->data.event.event);
+        //fprintf(stderr, "event: %d - '%s'\n", d->data.event.wv, d->data.event.event);fflush(stderr);
         return d;
     } else {
         return nullptr;
diff --git a/rktwebview_qt/rktwebview_qt.cpp b/rktwebview_qt/rktwebview_qt.cpp
index 31d9afc..dd99de1 100644
--- a/rktwebview_qt/rktwebview_qt.cpp
+++ b/rktwebview_qt/rktwebview_qt.cpp
@@ -31,6 +31,7 @@ void Rktwebview_qt::processCommand(Command *cmd)
     switch(cmd->cmd) {
     case COMMAND_QUIT: { // Quit application
         _app->quit();
+        cmd->done = true;
     }
     break;
     case COMMAND_NEW_CONTEXT: {
@@ -640,6 +641,8 @@ void Rktwebview_qt::rktQuit()
 {
     Command c(COMMAND_QUIT);
     postCommand(&c);
+
+    while(!c.done) { doEvents(); }
 }
 
 result_t Rktwebview_qt::fileDlg(rktwebview_t w, const char *title, const char *base, const char *filters,QFileDialog::FileMode mode, QFileDialog::AcceptMode am, QString evt_ok, QString evt_cancel)
diff --git a/rktwebview_qt/rktwebview_test.cpp b/rktwebview_qt/rktwebview_test.cpp
index eca74bb..9075755 100644
--- a/rktwebview_qt/rktwebview_test.cpp
+++ b/rktwebview_qt/rktwebview_test.cpp
@@ -1,16 +1,34 @@
 #include "rktwebview.h"
 #include <string>
+
+#ifdef _WIN32
+#include <windows.h>
+#else
 #include <unistd.h>
+#endif
+#include "utils.h"
 
 int main(int argc, char *argv[])
-{std::string me = argv[0];
-    int idx = me.rfind("/");
+{
+    std::string me = argv[0];
 
-    std::string loc = me.substr(0, idx);
+    std::string loc = basedir(me);
+#ifdef _WIN32
+    std::string prg = loc + "\\rktwebview_prg.exe";
+    SetDllDirectoryA("C:\\Qt\\6.10.2\\msvc2022_64\\bin");
+#else
     std::string prg = loc + "/rktwebview_prg";
+#endif
 
+#ifdef _WIN32
+    {
+        std::string e = std::string("RKT_WEBVIEW_PRG=") + prg;
+        _putenv(e.c_str());
+    }
+#else
     setenv("RKT_WEBVIEW_PRG", prg.c_str(), true);
     setenv("LD_LIBRARY_PATH", loc.c_str(), true);
+#endif
 
     int context = rkt_webview_new_context("", nullptr);
 
@@ -24,9 +42,13 @@ int main(int argc, char *argv[])
         rkt_data_t *d = rkt_webview_get_event();
         rkt_webview_free_data(d);
     }
+#ifdef _WIN32
+    Sleep(10);
+#else
     sleep(10);
+#endif
 
     rkt_webview_close(wv);
 
     rkt_webview_cleanup();
-}
\ No newline at end of file
+}
diff --git a/rktwebview_qt/rktwebview_types.h b/rktwebview_qt/rktwebview_types.h
index 51dcaea..e0b1e19 100644
--- a/rktwebview_qt/rktwebview_types.h
+++ b/rktwebview_qt/rktwebview_types.h
@@ -30,7 +30,8 @@ typedef enum {
     choose_dir_failed = 14,
     open_file_failed = 15,
     save_file_failed = 16,
-    failed = 17
+    failed = 17,
+    invalid_handle = 18
 } result_t;
 
 typedef struct {
diff --git a/rktwebview_qt/shm.cpp b/rktwebview_qt/shm.cpp
index e2b4b59..1a506a2 100644
--- a/rktwebview_qt/shm.cpp
+++ b/rktwebview_qt/shm.cpp
@@ -1,17 +1,6 @@
 #include "shm.h"
-
-#ifdef __linux
-
-#include <stdio.h>
-#include <stdlib.h>
 #include <string.h>
-#include <fcntl.h>
-#include <sys/shm.h>
-#include <sys/stat.h>
-#include <sys/mman.h>
-#include <unistd.h>
-#include <errno.h>
-#include <semaphore.h>
+#include <stdio.h>
 
 typedef struct __shm_item__ {
 
@@ -22,35 +11,26 @@ typedef struct __shm_item__ {
 } ShmItem;
 
 
-class ShmApi
+class ShmApiBase
 {
-private:
-    int     _shm_fd;
-    size_t  _size;
-    bool    _owner;
-    void   *_mem;
-    sem_t  *_sem;
+protected:
+    char    *_mem;
 
-    char *_mem_name;
-    char *_sem_name;
-
-    size_t  *_used;
+    int      *_used;
     ShmPlace *_slots;
     ShmPlace *_first;
     ShmPlace *_free_list;
 
+    char *_mem_name;
+    char *_sem_name;
+
     int    _in_critical;
-
-private:
-    void cleanup() {
-        // We don't need to do anything here.
-
-    }
+    size_t  _size;
+    bool    _owner;
 
 public:
-    ShmSem *makeSem(const char *name, bool owner) {
-        return new ShmSem(name, owner);
-    }
+    virtual void enterCritical() = 0;
+    virtual void leaveCritical() = 0;
 
 public:
     int slot(int s) {
@@ -71,7 +51,7 @@ public:
         if (place == SHM_NULL) {
             *p = nullptr;
         } else {
-            *p = reinterpret_cast<T *>(reinterpret_cast<char *>(_mem) + place);
+            *p = reinterpret_cast<T *>(_mem + place);
         }
     }
 
@@ -81,7 +61,7 @@ public:
             return nullptr;
         }
 
-        return reinterpret_cast<char *>(_mem) + place;
+        return _mem + place;
     }
 
 public:
@@ -125,7 +105,7 @@ public:
         } else {
             ShmPlace p_i = *_used;
             i = reinterpret_cast<ShmItem *>(reinterpret_cast<char *>(_mem) + p_i);
-            size_t u = *_used + sizeof(ShmItem) + bytes;
+            int u = static_cast<int>(*_used + sizeof(ShmItem) + bytes);
 
             if (u >= _size) {
                 place = SHM_NULL;
@@ -185,6 +165,66 @@ public:
         leaveCritical();
     }
 
+public:
+    ShmSem *makeSem(const char *name, bool owner) {
+        return new ShmSem(name, owner);
+    }
+
+public:
+    ShmApiBase(const char *name, size_t size, bool owner) {
+        char *buf = reinterpret_cast<char *>(malloc(strlen(name) + 50));
+        sprintf(buf, "sem_%s", name);
+        _sem_name = _strdup(buf);
+        _mem_name = _strdup(name);
+        ::free(buf);
+
+        _owner = owner;
+
+        _size = size;
+
+        _used = nullptr;
+        _slots = nullptr;
+        _first = nullptr;
+        _free_list = nullptr;
+        _mem = nullptr;
+
+        _in_critical = 0;
+    }
+
+    virtual ~ShmApiBase()
+    {
+        ::free(_sem_name);
+        ::free(_mem_name);
+    }
+};
+
+#ifdef __linux
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <fcntl.h>
+#include <sys/shm.h>
+#include <sys/stat.h>
+#include <sys/mman.h>
+#include <unistd.h>
+#include <errno.h>
+#include <semaphore.h>
+
+
+class ShmApi : public ShmApiBase
+{
+private:
+    int     _shm_fd;
+    sem_t  *_sem;
+
+private:
+    void cleanup() {
+        // We don't need to do anything here.
+
+    }
+
+public:
     void enterCritical() {
         if (_in_critical > 0) {
             _in_critical++;
@@ -204,19 +244,17 @@ public:
     }
 
 public:
-    ShmApi(const char *name, size_t size, bool owner) {
-
-        {
-            char buf[strlen(name) + 50];
-            sprintf(buf, "sem_%s", name);
-            _sem_name = strdup(buf);
-            _mem_name = strdup(name);
-        }
+    bool isValid() {
+        return true;
+    }
 
+public:
+    ShmApi(const char *name, size_t size, bool owner) : ShmApiBase(name, size, owner)
+    {
         size_t slots_size = sizeof(ShmPlace) * SHM_MAX_SLOTS;
         size += slots_size;
 
-        if (owner) {
+        if (_owner) {
             _sem = sem_open(_sem_name, O_RDWR | O_CREAT, S_IRUSR | S_IWUSR, 0);
             _shm_fd = shm_open(name, O_CREAT | O_RDWR, 0600);
             ftruncate(_shm_fd, size);
@@ -224,21 +262,18 @@ public:
             _sem = sem_open(_sem_name, O_RDWR, S_IRUSR | S_IWUSR, 0);
             _shm_fd = shm_open(name, O_RDWR, 0600);
         }
-        _size = size;
         _mem = mmap(nullptr, _size, PROT_READ|PROT_WRITE, MAP_SHARED, _shm_fd, 0);
 
-        _slots = reinterpret_cast <ShmPlace *>(reinterpret_cast<char *>(_mem) + sizeof(size_t) + sizeof(ShmPlace) + sizeof(ShmPlace));
-        _used = reinterpret_cast<size_t *>(_mem);
+        _slots = reinterpret_cast <ShmPlace *>(_mem + sizeof(int) + sizeof(ShmPlace) + sizeof(ShmPlace));
+        _used = reinterpret_cast<int *>(_mem);
 
-        _first = reinterpret_cast<ShmPlace *>(reinterpret_cast<char *>(_mem) + sizeof(size_t));
-        _free_list = reinterpret_cast<ShmPlace *>(reinterpret_cast<char *>(_mem) + sizeof(size_t) + sizeof(ShmPlace));
-
-        _owner = owner;
+        _first = reinterpret_cast<ShmPlace *>(_mem + sizeof(int));
+        _free_list = reinterpret_cast<ShmPlace *>(_mem + sizeof(int) + sizeof(ShmPlace));
 
         if (_owner) {
             *_first = SHM_NULL;
             *_free_list = SHM_NULL;
-            *_used = sizeof(size_t) + sizeof(ShmItem *) + sizeof(ShmItem *) + slots_size;
+            *_used = sizeof(int) + sizeof(ShmItem *) + sizeof(ShmItem *) + slots_size;
             sem_post(_sem);
         }
 
@@ -254,44 +289,241 @@ public:
             shm_unlink(_mem_name);
             sem_unlink(_sem_name);
         }
-        ::free(_mem_name);
-        ::free(_sem_name);
     }
 };
+
+class ShmSemApi {
+    private:
+        sem_t *_sem;
+        char  *_name;
+        bool   _owner;
+
+    public:
+        void post() {
+            sem_post(_sem);
+        }
+
+        void wait() {
+            int r = sem_wait(_sem);
+            if (r != 0) {
+                fprintf(stderr, "sem_wait error: %d, %s\n", errno, strerror(errno));
+            }
+        }
+
+        bool trywait() {
+            int r = sem_trywait(reinterpret_cast<sem_t *>(_sem));
+            if (r != 0 && r != EAGAIN) {
+                fprintf(stderr, "sem_wait error: %d, %s\n", errno, strerror(errno));
+            }
+
+            return (r == 0);
+        }
+
+    public:
+        ShmSemApi(const char *n, bool owner) {
+            _name = strdup(n);
+
+            sem_t *s;
+            if (owner) {
+                s = sem_open(n, O_RDWR | O_CREAT, S_IRUSR | S_IWUSR, 0);
+            } else {
+                s = sem_open(n, O_RDWR, S_IRUSR | S_IWUSR, 0);
+            }
+            _sem = s;
+            _owner = owner;
+        }
+
+        virtual ~ShmSemApi() {
+            sem_close(_sem);
+            if (_owner) {
+                sem_unlink(_name);
+            }
+            free(_name);
+        }
+    };
+};
+
+public:
+};
 #endif
 
 #ifdef _WIN32
-class ShmApi
+#include <windows.h>
+
+class ShmApi : public ShmApiBase
 {
+private:
+    HANDLE      _shm_handle;
+    HANDLE      _sem_handle;
+    bool        _valid;
+
 public:
-    ShmApi(const char *name, size_t size, bool owner)
+    ShmApi(const char *name, size_t size, bool owner) : ShmApiBase(name, size, owner)
     {
+        size_t slots_size = sizeof(ShmPlace) * SHM_MAX_SLOTS;
+        size += slots_size;
+
+        _valid = true;
+        if (_owner) {
+            _shm_handle = CreateFileMappingA(INVALID_HANDLE_VALUE,
+                                            NULL,
+                                            PAGE_READWRITE,
+                                            0,
+                                            static_cast<DWORD>(size),                // size must be smaller < 2GB
+                                            name);
+
+            if (_shm_handle == NULL) {
+                fprintf(stderr, "Cannot create shared memory with name %s and size %lld\n", name, size);
+                _valid = false;
+            }
+        } else {
+            _shm_handle = OpenFileMappingA(FILE_MAP_ALL_ACCESS,
+                                          FALSE,
+                                          name);
+            if (_shm_handle == NULL) {
+                fprintf(stderr, "Cannot open shared memory with name %s\n", name);
+                _valid = false;
+            }
+        }
+
+        if (_valid) {
+            _mem = static_cast<LPSTR>(MapViewOfFile(_shm_handle,
+                                                    FILE_MAP_ALL_ACCESS,
+                                                    0,
+                                                    0,
+                                                    size));
+            if (_mem == NULL) {
+                fprintf(stderr, "Cannot map shared memory, errorcode = %ld\n", GetLastError());
+                _valid = false;
+                CloseHandle(_shm_handle);
+            }
+        }
+
+        if (_valid) {
+            if (_owner) {
+                _sem_handle = CreateSemaphoreA(NULL,
+                                              1,
+                                              10000,
+                                              _sem_name
+                                              );
+            } else {
+                _sem_handle = OpenSemaphoreA(SYNCHRONIZE|SEMAPHORE_MODIFY_STATE, FALSE, _sem_name);
+            }
+            if (_sem_handle == NULL) {
+                fprintf(stderr, "Cannot create or open semaphore with name '%s' (%ld)\n", _sem_name, GetLastError());
+                UnmapViewOfFile(_mem);
+                CloseHandle(_shm_handle);
+                _valid = false;
+            }
+        }
+
+        if (_valid) {
+            _slots = reinterpret_cast <ShmPlace *>(_mem + sizeof(int) + sizeof(ShmPlace) + sizeof(ShmPlace));
+            _used = reinterpret_cast<int *>(_mem);
+
+            _first = reinterpret_cast<ShmPlace *>(_mem + sizeof(int));
+            _free_list = reinterpret_cast<ShmPlace *>(_mem + sizeof(int) + sizeof(ShmPlace));
+
+            if (_owner) {
+                *_first = SHM_NULL;
+                *_free_list = SHM_NULL;
+                *_used = sizeof(int) + sizeof(ShmItem *) + sizeof(ShmItem *) + slots_size;
+            }
+        }
     }
 
     ~ShmApi()
     {
+        if (_valid) {
+            UnmapViewOfFile(_mem);
+            CloseHandle(_shm_handle);
+            CloseHandle(_sem_handle);
+        }
+    }
+
+    bool isValid() {
+        return _valid;
     }
 
     void enterCritical()
     {
-
+        if (_in_critical > 0) {
+            _in_critical++;
+        } else {
+            WaitForSingleObject(_sem_handle, INFINITE);
+            _in_critical = 1;
+        }
     }
 
     void leaveCritical()
     {
-
+        if (_in_critical > 1) {
+            _in_critical--;
+        } else {
+            _in_critical = 0;
+            ReleaseSemaphore(_sem_handle, 1, NULL);
+        }
     }
 
-    void *alloc(size_t bytes)
+    ShmSem *sem(const char *name, bool owner)
     {
-        return malloc(bytes);
+        return nullptr;
+    }
+};
+
+
+class ShmSemApi {
+private:
+    HANDLE _sem;
+    char  *_name;
+    bool   _owner;
+
+public:
+    void post() {
+        ReleaseSemaphore(_sem, 1, NULL);
     }
 
-    void free(void *mem)
-    {
-        free(mem);
+    void wait() {
+        DWORD r = WaitForSingleObject(_sem, INFINITE);
+        if (r != WAIT_OBJECT_0) {
+            fprintf(stderr, "sem_wait error: %ld\n", r);
+        }
     }
-}
+
+    bool trywait() {
+        DWORD r = WaitForSingleObject(_sem , 0);
+        if (r != WAIT_OBJECT_0 && r != WAIT_TIMEOUT) {
+            fprintf(stderr, "sem_wait error: %ld\n", r);
+        }
+        return r == WAIT_OBJECT_0;
+    }
+
+public:
+    ShmSemApi(const char *n, bool owner) {
+        _name = _strdup(n);
+
+        if (owner) {
+            _sem = CreateSemaphoreA(NULL,
+                                   0,
+                                   10000,
+                                   _name);
+        } else {
+            _sem = OpenSemaphoreA(SYNCHRONIZE|SEMAPHORE_MODIFY_STATE, FALSE, _name);
+        }
+
+        if (_sem == NULL) {
+            fprintf(stderr, "Cannot create or open semaphore with name '%s'\n", _name);
+        }
+        _owner = owner;
+    }
+
+    virtual ~ShmSemApi() {
+        if (_sem != NULL) {
+            CloseHandle(_sem);
+        }
+    }
+};
+
 #endif
 
 
@@ -326,6 +558,11 @@ ShmSem *Shm::sem(const char *name, bool owner)
     return _shm_api->makeSem(name, owner);
 }
 
+bool Shm::isValid()
+{
+    return _shm_api->isValid();
+}
+
 const char *Shm::name()
 {
     return _shm_api->name();
@@ -352,44 +589,22 @@ Shm::~Shm()
 }
 
 
-
 void ShmSem::post() {
-    sem_post(reinterpret_cast<sem_t *>(_sem));
+    _api->post();
 }
 
 void ShmSem::wait() {
-    int r = sem_wait(reinterpret_cast<sem_t *>(_sem));
-    if (r != 0) {
-        fprintf(stderr, "sem_wait error: %d, %s\n", errno, strerror(errno));
-    }
+    _api->wait();
 }
 
 bool ShmSem::trywait() {
-    int r = sem_trywait(reinterpret_cast<sem_t *>(_sem));
-    if (r != 0 && r != EAGAIN) {
-        fprintf(stderr, "sem_wait error: %d, %s\n", errno, strerror(errno));
-    }
-
-    return (r == 0);
+    return _api->trywait();
 }
 
 ShmSem::ShmSem(const char *n, bool owner) {
-    _name = strdup(n);
-
-    sem_t *s;
-    if (owner) {
-        s = sem_open(n, O_RDWR | O_CREAT, S_IRUSR | S_IWUSR, 0);
-    } else {
-        s = sem_open(n, O_RDWR, S_IRUSR | S_IWUSR, 0);
-    }
-    _sem = reinterpret_cast<void *>(s);
-    _owner = owner;
+    _api = new ShmSemApi(n, owner);
 }
 
 ShmSem::~ShmSem() {
-    sem_close(reinterpret_cast<sem_t *>(_sem));
-    if (_owner) {
-        sem_unlink(_name);
-    }
-    free(_name);
+    delete _api;
 }
diff --git a/rktwebview_qt/shm.h b/rktwebview_qt/shm.h
index 1b567df..8de1d08 100644
--- a/rktwebview_qt/shm.h
+++ b/rktwebview_qt/shm.h
@@ -4,6 +4,7 @@
 #include <stdlib.h>
 
 class ShmApi;
+class ShmSemApi;
 typedef int ShmPlace;
 typedef int ShmSlot;
 
@@ -12,9 +13,7 @@ typedef int ShmSlot;
 
 class ShmSem {
 private:
-    void *_sem;
-    char *_name;
-    bool _owner;
+    ShmSemApi *_api;
 
 public:
     void post();
@@ -44,6 +43,9 @@ public:
 public:
     ShmSem *sem(const char *name, bool owner);
 
+public:
+    bool isValid();
+
 public:
     const char *name();
 
diff --git a/rktwebview_qt/utils.h b/rktwebview_qt/utils.h
new file mode 100644
index 0000000..b8284c3
--- /dev/null
+++ b/rktwebview_qt/utils.h
@@ -0,0 +1,29 @@
+#ifndef UTILS_H
+#define UTILS_H
+
+#include <string>
+
+inline std::string basedir(const std::string &path)
+{
+    int idx1 = path.rfind("/");
+    int idx2 = path.rfind("\\");
+    std::string r;
+    if (idx1 == std::string::npos && idx2 == std::string::npos) {
+        r = "";
+    } else {
+        int idx;
+        if (idx1 == std::string::npos) {
+            idx = idx2;
+        } else if (idx2 == std::string::npos) {
+            idx = idx1;
+        } else if (idx1 < idx2) {
+            idx = idx2;
+        } else {
+            idx = idx1;
+        }
+        r = path.substr(0, idx);
+    }
+    return r;
+}
+
+#endif // UTILS_H