server: Ignore low word of a class instance when looking up for a window class.

dlls/user32/tests/class.c

@@ -128,14 +128,11 @@ static void ClassTest(HINSTANCE hInstance, BOOL global)
        WS_OVERLAPPEDWINDOW + WS_HSCROLL + WS_VSCROLL,
        CW_USEDEFAULT, 0, CW_USEDEFAULT, 0, 0,
        0, hInstance2, 0);
-todo_wine_if (!global)
     ok(hTestWnd != 0, "Failed to create window for hInstance %p\n", hInstance2);
 
-todo_wine_if (!global)
     ok((HINSTANCE)GetClassLongPtrA(hTestWnd, GCLP_HMODULE) == hInstance,
        "Wrong GCL instance %p != %p\n",
        (HINSTANCE)GetClassLongPtrA(hTestWnd, GCLP_HMODULE), hInstance);
-todo_wine_if (!global)
     ok((HINSTANCE)GetWindowLongPtrA(hTestWnd, GWLP_HINSTANCE) == hInstance2,
        "Wrong GWL instance %p != %p\n",
        (HINSTANCE)GetWindowLongPtrA(hTestWnd, GWLP_HINSTANCE), hInstance2);

server/class.c

@@ -100,9 +100,12 @@ static struct window_class *find_class( struct process *process, atom_t atom, mo
 
     LIST_FOR_EACH( ptr, &process->classes )
     {
+        int is_win16;
         struct window_class *class = LIST_ENTRY( ptr, struct window_class, entry );
         if (class->atom != atom) continue;
-        if (!instance || !class->local || class->instance == instance) return class;
+        is_win16 = !(class->instance >> 16);
+        if (!instance || !class->local || class->instance == instance ||
+            (!is_win16 && ((class->instance & ~0xffff) == (instance & ~0xffff)))) return class;
     }
     return NULL;
 }