win32: Fix maximized windows when leaving fullscreen

If a window is fullscreen and the maximized state is requested, it needs to be explicitly entered after leaving fullscreen, or the resulting window will be in the maximized state, but still the size of the non-maximized window.

src/video/windows/SDL_windowswindow.c

@@ -1088,24 +1088,29 @@ void WIN_RaiseWindow(SDL_VideoDevice *_this, SDL_Window *window)
 void WIN_MaximizeWindow(SDL_VideoDevice *_this, SDL_Window *window)
 {
     SDL_WindowData *data = window->driverdata;
-    HWND hwnd = data->hwnd;
-    data->expected_resize = SDL_TRUE;
-    ShowWindow(hwnd, SW_MAXIMIZE);
-    data->expected_resize = SDL_FALSE;
-
-    /* Clamp the maximized window size to the max window size.
-     * This is automatic if maximizing from the window controls.
-     */
-    if (window->max_w || window->max_h) {
-        int fx, fy, fw, fh;
-
-        window->windowed.w = window->max_w ? SDL_min(window->w, window->max_w) : window->windowed.w;
-        window->windowed.h = window->max_h ? SDL_min(window->h, window->max_h) : window->windowed.h;
-        WIN_AdjustWindowRect(window, &fx, &fy, &fw, &fh, SDL_WINDOWRECT_WINDOWED);
 
+    if (!(window->flags & SDL_WINDOW_FULLSCREEN)) {
+        HWND hwnd = data->hwnd;
         data->expected_resize = SDL_TRUE;
-        SetWindowPos(hwnd, HWND_TOP, fx, fy, fw, fh, data->copybits_flag | SWP_NOMOVE | SWP_NOOWNERZORDER | SWP_NOACTIVATE);
+        ShowWindow(hwnd, SW_MAXIMIZE);
         data->expected_resize = SDL_FALSE;
+
+        /* Clamp the maximized window size to the max window size.
+         * This is automatic if maximizing from the window controls.
+         */
+        if (window->max_w || window->max_h) {
+            int fx, fy, fw, fh;
+
+            window->windowed.w = window->max_w ? SDL_min(window->w, window->max_w) : window->windowed.w;
+            window->windowed.h = window->max_h ? SDL_min(window->h, window->max_h) : window->windowed.h;
+            WIN_AdjustWindowRect(window, &fx, &fy, &fw, &fh, SDL_WINDOWRECT_WINDOWED);
+
+            data->expected_resize = SDL_TRUE;
+            SetWindowPos(hwnd, HWND_TOP, fx, fy, fw, fh, data->copybits_flag | SWP_NOMOVE | SWP_NOOWNERZORDER | SWP_NOACTIVATE);
+            data->expected_resize = SDL_FALSE;
+        }
+    }else {
+        data->windowed_mode_was_maximized = SDL_TRUE;
     }
 }
 
@@ -1152,10 +1157,14 @@ void WIN_SetWindowAlwaysOnTop(SDL_VideoDevice *_this, SDL_Window *window, SDL_bo
 void WIN_RestoreWindow(SDL_VideoDevice *_this, SDL_Window *window)
 {
     SDL_WindowData *data = window->driverdata;
-    HWND hwnd = data->hwnd;
-    data->expected_resize = SDL_TRUE;
-    ShowWindow(hwnd, SW_RESTORE);
-    data->expected_resize = SDL_FALSE;
+    if (!(window->flags & SDL_WINDOW_FULLSCREEN)) {
+        HWND hwnd = data->hwnd;
+        data->expected_resize = SDL_TRUE;
+        ShowWindow(hwnd, SW_RESTORE);
+        data->expected_resize = SDL_FALSE;
+    } else {
+        data->windowed_mode_was_maximized = SDL_FALSE;
+    }
 }
 
 static DWM_WINDOW_CORNER_PREFERENCE WIN_UpdateCornerRoundingForHWND(HWND hwnd, DWM_WINDOW_CORNER_PREFERENCE cornerPref)
@@ -1210,6 +1219,7 @@ int WIN_SetWindowFullscreen(SDL_VideoDevice *_this, SDL_Window *window, SDL_Vide
     HWND top;
     int x, y;
     int w, h;
+    SDL_bool enterMaximized = SDL_FALSE;
 
 #ifdef HIGHDPI_DEBUG
     SDL_Log("WIN_SetWindowFullscreen: %d", (int)fullscreen);
@@ -1274,6 +1284,7 @@ int WIN_SetWindowFullscreen(SDL_VideoDevice *_this, SDL_Window *window, SDL_Vide
         */
         if (data->windowed_mode_was_maximized && !data->in_window_deactivation) {
             style |= WS_MAXIMIZE;
+            enterMaximized = SDL_TRUE;
         }
 
         menu = (style & WS_CHILDWINDOW) ? FALSE : (GetMenu(hwnd) != NULL);
@@ -1285,7 +1296,13 @@ int WIN_SetWindowFullscreen(SDL_VideoDevice *_this, SDL_Window *window, SDL_Vide
     }
     SetWindowLong(hwnd, GWL_STYLE, style);
     data->expected_resize = SDL_TRUE;
-    SetWindowPos(hwnd, top, x, y, w, h, data->copybits_flag | SWP_NOACTIVATE);
+
+    if (!enterMaximized) {
+        SetWindowPos(hwnd, top, x, y, w, h, data->copybits_flag | SWP_NOACTIVATE);
+    } else {
+        WIN_MaximizeWindow(_this, window);
+    }
+
     data->expected_resize = SDL_FALSE;
 
 #ifdef HIGHDPI_DEBUG