Fix the way to check terminal field in interactive form

core/fpdfdoc/cpdf_interform.cpp

 // Copyright 2016 PDFium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
 
 #include "core/fpdfdoc/cpdf_interform.h"
 
 #include <utility>
 #include <vector>
@@ skipping 1061 matching lines @@
     return;
 
   for (size_t i = 0; i < pAnnots->GetCount(); i++) {
     CPDF_Dictionary* pAnnot = pAnnots->GetDictAt(i);
     if (pAnnot && pAnnot->GetStringFor("Subtype") == "Widget")
       LoadField(pAnnot, 0);
   }
 }
 
 CPDF_FormField* CPDF_InterForm::AddTerminalField(CPDF_Dictionary* pFieldDict) {
-  if (!pFieldDict->KeyExist("T"))
-    return nullptr;
+  if (!pFieldDict->KeyExist("FT")) {
+    // Key "FT" is required for terminal fields, it is also inheritable.
+    CPDF_Dictionary* pParentDict = pFieldDict->GetDictFor("Parent");
+    if (!pParentDict || !pParentDict->KeyExist("FT"))
+      return nullptr;
+  }
 
   CPDF_Dictionary* pDict = pFieldDict;
   CFX_WideString csWName = FPDF_GetFullName(pFieldDict);
   if (csWName.IsEmpty())
     return nullptr;
 
   CPDF_FormField* pField = nullptr;
   pField = m_pFieldTree->GetField(csWName);
   if (!pField) {
     CPDF_Dictionary* pParent = pFieldDict;
@@ skipping 216 matching lines @@
     else if (iType == FIELDTYPE_LISTBOX)
       m_pFormNotify->AfterSelectionChange(pField);
     else if (iType == FIELDTYPE_COMBOBOX || iType == FIELDTYPE_TEXTFIELD)
       m_pFormNotify->AfterValueChange(pField);
   }
 }
 
 void CPDF_InterForm::SetFormNotify(IPDF_FormNotify* pNotify) {
   m_pFormNotify = pNotify;
 }