Relax the share mode validation for transacted storage, with a test.

dlls/ole32/storage32.c

@@ -5802,15 +5802,16 @@ HRESULT WINAPI StgOpenStorage(
   /*
    * Validate the sharing mode
    */
-  switch(STGM_SHARE_MODE(grfMode))
-  {
-  case STGM_SHARE_EXCLUSIVE:
-  case STGM_SHARE_DENY_WRITE:
-    break;
-  default:
-    hr = STG_E_INVALIDFLAG;
-    goto end;
-  }
+  if (!(grfMode & STGM_TRANSACTED))
+    switch(STGM_SHARE_MODE(grfMode))
+    {
+      case STGM_SHARE_EXCLUSIVE:
+      case STGM_SHARE_DENY_WRITE:
+        break;
+      default:
+        hr = STG_E_INVALIDFLAG;
+        goto end;
+    }
 
   /*
    * Validate the STGM flags

dlls/ole32/tests/storage32.c

@@ -393,6 +393,14 @@ static void test_open_storage(void)
     ok(r==STG_E_INVALIDFLAG, "StgOpenStorage failed\n");
 
     /* open it for real */
+    r = StgOpenStorage( filename, NULL, STGM_SHARE_DENY_NONE | STGM_READ | STGM_TRANSACTED, NULL, 0, &stg); /* XLViewer 97/2000 */
+    ok(r==S_OK, "StgOpenStorage failed\n");
+    if(stg)
+    {
+        r = IStorage_Release(stg);
+        ok(r == 0, "wrong ref count\n");
+    }
+
     r = StgOpenStorage( filename, NULL, STGM_SHARE_DENY_WRITE | STGM_READ, NULL, 0, &stg);
     ok(r==S_OK, "StgOpenStorage failed\n");
     if(stg)