tray(Win32): re-add the tray icon upon taskbar restart

src/tray/SDL_tray_utils.c

@@ -83,6 +83,11 @@ void SDL_CleanupTrays(void)
         SDL_DestroyTray((SDL_Tray *)trays[i]);
     }
     SDL_free(trays);
+
+    SDL_PropertiesID g = SDL_GetGlobalProperties();
+    if (g) {
+        SDL_ClearProperty(g, SDL_PROP_TRAY_CLEANUP);
+    }
 }
 
 bool SDL_HasActiveTrays(void)

src/tray/SDL_tray_utils.h

@@ -20,6 +20,8 @@
 */
 #include "SDL_internal.h"
 
+#define SDL_PROP_TRAY_CLEANUP "SDL.PROP.Tray.Cleanup"
+
 extern void SDL_RegisterTray(SDL_Tray *tray);
 extern void SDL_UnregisterTray(SDL_Tray *tray);
 extern void SDL_CleanupTrays(void);

src/tray/windows/SDL_tray.c

@@ -111,11 +111,20 @@ LRESULT CALLBACK TrayWindowProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lPar
         return DefWindowProc(hwnd, uMsg, wParam, lParam);
     }
 
+    static UINT s_taskbarRestart = 0;
+    if (s_taskbarRestart == 0) {
+        s_taskbarRestart = RegisterWindowMessage(TEXT("TaskbarCreated"));
+    }
+    if(uMsg == s_taskbarRestart) {
+        Shell_NotifyIconW(NIM_ADD, &tray->nid);
+        Shell_NotifyIconW(NIM_SETVERSION, &tray->nid);
+    }
+
     switch (uMsg) {
         case WM_TRAYICON:
             if (LOWORD(lParam) == WM_CONTEXTMENU || LOWORD(lParam) == WM_LBUTTONUP) {
                 SetForegroundWindow(hwnd);
-                
+
                 if (tray->menu) {
                     TrackPopupMenu(tray->menu->hMenu, TPM_BOTTOMALIGN | TPM_RIGHTALIGN, GET_X_LPARAM(wParam), GET_Y_LPARAM(wParam), 0, hwnd, NULL);
                 }
@@ -216,6 +225,51 @@ void SDL_UpdateTrays(void)
 {
 }
 
+static void SDL_PropTrayCleanupCb(void* userdata, void* cls) {
+    WNDCLASSEX wcex;
+
+    wcex.hIcon = NULL;
+    wcex.hIconSm = NULL;
+    HINSTANCE h = GetModuleHandle(NULL);
+    if (GetClassInfoEx(h, cls, &wcex)) {
+        UnregisterClass(cls, h);
+    }
+}
+
+static bool SDL_RegisterTrayClass(LPCWSTR className)
+{
+    SDL_PropertiesID g = SDL_GetGlobalProperties();
+    if (!g) {
+        return false;
+    }
+    void* p = SDL_GetPointerProperty(g, SDL_PROP_TRAY_CLEANUP, NULL);
+    if (p) {
+        return true;
+    }
+
+    WNDCLASSEX wcex;
+
+    wcex.cbSize = sizeof(WNDCLASSEX);
+    wcex.hCursor = NULL;
+    wcex.hIcon = NULL;
+    wcex.hIconSm = NULL;
+    wcex.lpszMenuName = NULL;
+    wcex.lpszClassName = className;
+    wcex.style = 0;
+    wcex.hbrBackground = NULL;
+    wcex.lpfnWndProc = TrayWindowProc;
+    wcex.hInstance = NULL;
+    wcex.cbClsExtra = 0;
+    wcex.cbWndExtra = 0;
+
+    if (!RegisterClassEx(&wcex)) {
+        return SDL_SetError("Couldn't register tray class");
+    }
+
+    SDL_SetPointerPropertyWithCleanup(g, SDL_PROP_TRAY_CLEANUP, (void*)wcex.lpszClassName, SDL_PropTrayCleanupCb, NULL);
+    return true;
+}
+
 SDL_Tray *SDL_CreateTray(SDL_Surface *icon, const char *tooltip)
 {
     if (!SDL_IsMainThread()) {
@@ -230,8 +284,12 @@ SDL_Tray *SDL_CreateTray(SDL_Surface *icon, const char *tooltip)
     }
 
     tray->menu = NULL;
-    tray->hwnd = CreateWindowEx(0, TEXT("Message"), NULL, 0, 0, 0, 0, 0, HWND_MESSAGE, NULL, NULL, NULL);
-    SetWindowLongPtr(tray->hwnd, GWLP_WNDPROC, (LONG_PTR) TrayWindowProc);
+    if (!SDL_RegisterTrayClass(TEXT("SDL_TRAY"))) {
+        SDL_SetError("Failed to register SDL_TRAY window class");
+        return NULL;
+    }
+    tray->hwnd = CreateWindowEx(0, TEXT("SDL_TRAY"), NULL, WS_OVERLAPPEDWINDOW,
+                                CW_USEDEFAULT, 0, CW_USEDEFAULT, 0, NULL, NULL, NULL, NULL);
 
     WIN_UpdateDarkModeForHWND(tray->hwnd);