Implemented SDL_WINDOW_SKIP_TASKBAR on Windows

src/video/windows/SDL_windowswindow.c

@@ -91,7 +91,7 @@ WIN_SetWindowPositionInternal(_THIS, SDL_Window * window, UINT flags)
     int w, h;
 
     /* Figure out what the window area will be */
-    if (SDL_ShouldAllowTopmost() && ((window->flags & (SDL_WINDOW_FULLSCREEN|SDL_WINDOW_INPUT_FOCUS)) == (SDL_WINDOW_FULLSCREEN|SDL_WINDOW_INPUT_FOCUS) || window->flags & SDL_WINDOW_ALWAYS_ON_TOP)) {
+    if (SDL_ShouldAllowTopmost() && ((window->flags & (SDL_WINDOW_FULLSCREEN|SDL_WINDOW_INPUT_FOCUS)) == (SDL_WINDOW_FULLSCREEN|SDL_WINDOW_INPUT_FOCUS) || (window->flags & SDL_WINDOW_ALWAYS_ON_TOP))) {
         top = HWND_TOPMOST;
     } else {
         top = HWND_NOTOPMOST;
@@ -268,12 +268,16 @@ SetupWindowData(_THIS, SDL_Window * window, HWND hwnd, SDL_bool created)
 int
 WIN_CreateWindow(_THIS, SDL_Window * window)
 {
-    HWND hwnd;
+    HWND hwnd, parent = NULL;
     RECT rect;
     DWORD style = STYLE_BASIC;
     int x, y;
     int w, h;
 
+    if (window->flags & SDL_WINDOW_SKIP_TASKBAR) {
+        parent = CreateWindow(SDL_Appname, TEXT(""), STYLE_BASIC, 0, 0, 32, 32, NULL, NULL, SDL_Instance, NULL);
+    }
+
     style |= GetWindowStyle(window);
 
     /* Figure out what the window area will be */
@@ -288,7 +292,7 @@ WIN_CreateWindow(_THIS, SDL_Window * window)
     h = (rect.bottom - rect.top);
 
     hwnd =
-        CreateWindow(SDL_Appname, TEXT(""), style, x, y, w, h, NULL, NULL,
+        CreateWindow(SDL_Appname, TEXT(""), style, x, y, w, h, parent, NULL,
                      SDL_Instance, NULL);
     if (!hwnd) {
         return WIN_SetError("Couldn't create window");