user32: DdeQueryString returns a NULL str if there is no handle.

dlls/user32/dde_misc.c

@@ -348,8 +348,8 @@ UINT WDML_Initialize(LPDWORD pidInst, PFNCALLBACK pfnCallback,
     UINT			ret;
     WNDCLASSEXW			wndclass;
 
-    TRACE("(%p,%p,0x%x,%d)\n",
-	  pidInst, pfnCallback, afCmd, ulRes);
+    TRACE("(%p,%p,0x%x,%d,0x%x)\n",
+	  pidInst, pfnCallback, afCmd, ulRes, bUnicode);
 
     if (ulRes)
     {
@@ -999,6 +999,14 @@ static int	WDML_QueryString(WDML_INSTANCE* pInstance, HSZ hsz, LPVOID ptr, DWORD
 	cchMax = MAX_BUFFER_LEN;
     }
 
+    /* if there is no input windows returns a NULL string */
+    if (hsz == NULL)
+    {
+	CHAR *t_ptr = ptr;
+	*t_ptr = '\0';
+	return 1;
+    }
+
     switch (codepage)
     {
     case CP_WINANSI:

dlls/user32/tests/dde.c

@@ -654,7 +654,6 @@ static HDDEDATA CALLBACK server_ddeml_callback(UINT uType, UINT uFmt, HCONV hcon
 
         if (msg_index == 5)
         {
-            todo_wine
             {
                 ok(!lstrcmpA(str, ""), "Expected empty string, got %s\n", str);
                 ok(size == 1, "Expected 1, got %d\n", size);
@@ -696,7 +695,6 @@ static HDDEDATA CALLBACK server_ddeml_callback(UINT uType, UINT uFmt, HCONV hcon
         size = DdeQueryStringA(server_pid, hsz2, str, MAX_PATH, CP_WINANSI);
         if (msg_index == 7)
         {
-            todo_wine
             {
                 ok(!lstrcmpA(str, ""), "Expected empty string, got %s\n", str);
                 ok(size == 1, "Expected 1, got %d\n", size);