diff --git a/BUGS.md b/BUGS.md
index 55a96a2..85d7255 100644
--- a/BUGS.md
+++ b/BUGS.md
@@ -1,6 +1,7 @@
 
 # BUGS
 
+- testar se perguntas regex funcionam com yaml.safe_load.
 - safari as vezes envia dois gets no inicio do topico. nesses casos, a segunda pergunta não é actualizada no browser... o topico tem de ser gerado qd se escolhe o topico em main_topics. O get nao deve alterar o estado.
 - click numa opcao checkbox fora da checkbox+label não está a funcionar.
 - shift-enter não está a funcionar
diff --git a/aprendizations/factory.py b/aprendizations/factory.py
index ea9178a..cbc3739 100644
--- a/aprendizations/factory.py
+++ b/aprendizations/factory.py
@@ -48,17 +48,17 @@ class QFactory(object):
     # Depending on the type of question, a different question class will be
     # instantiated. All these classes derive from the base class `Question`.
     _types = {
-        'radio':        QuestionRadio,
-        'checkbox':     QuestionCheckbox,
-        'text':         QuestionText,
-        'text-regex':   QuestionTextRegex,
+        'radio':            QuestionRadio,
+        'checkbox':         QuestionCheckbox,
+        'text':             QuestionText,
+        'text-regex':       QuestionTextRegex,
         'numeric-interval': QuestionNumericInterval,
-        'textarea':     QuestionTextArea,
+        'textarea':         QuestionTextArea,
         # -- informative panels --
-        'information':  QuestionInformation,
-        'warning':      QuestionInformation,
-        'alert':        QuestionInformation,
-        'success':      QuestionInformation,
+        'information':      QuestionInformation,
+        'warning':          QuestionInformation,
+        'alert':            QuestionInformation,
+        'success':          QuestionInformation,
         }
 
     def __init__(self, question_dict={}):
@@ -69,7 +69,7 @@ class QFactory(object):
     # i.e. a question object (radio, checkbox, ...).
     # -----------------------------------------------------------------------
     # async def generate_async(self):
-    #     loop = asyncio.get_event_loop()
+    #     loop = asyncio.get_running_loop()
     #     return await loop.run_in_executor(None, self.generate)
 
     def generate(self):
diff --git a/aprendizations/knowledge.py b/aprendizations/knowledge.py
index 3f7d99a..1adc8f0 100644
--- a/aprendizations/knowledge.py
+++ b/aprendizations/knowledge.py
@@ -43,34 +43,33 @@ class StudentKnowledge(object):
         now = datetime.now()
         for tref, s in self.state.items():
             dt = now - s['date']
-            s['level'] *= 0.95 ** dt.days   # forgetting factor 0.95 FIXME
+            s['level'] *= 0.98 ** dt.days   # forgetting factor 0.95 FIXME
 
     # ------------------------------------------------------------------------
     # Unlock topics whose dependencies are satisfied (> min_level)
     # ------------------------------------------------------------------------
     def unlock_topics(self):
-        # minimum level that the dependencies of a topic must have
-        # for the topic to be unlocked.
-        min_level = 0.01
-
         for topic in self.deps.nodes():
             if topic not in self.state:  # if locked
                 pred = self.deps.predecessors(topic)
+                min_level = self.deps.node[topic]['min_level']
                 if all(d in self.state and self.state[d]['level'] > min_level
-                   for d in pred):  # all dependencies are done
+                   for d in pred):  # all deps are greater than min_level
 
                     self.state[topic] = {
                         'level': 0.0,           # unlocked
                         'date': datetime.now()
                         }
                     logger.debug(f'Unlocked "{topic}".')
+                # else:  # lock this topic if deps do not satisfy min_level
+                #     del self.state[topic]
 
     # ------------------------------------------------------------------------
     # Start a new topic.
     #    questions: list of generated questions to do in the topic
     #    current_question: the current question to be presented
     # ------------------------------------------------------------------------
-    # FIXME async mas nao tem awaits...
+    # FIXME async mas nao tem awaits... do not allow restart same topic
     async def start_topic(self, topic):
         logger.debug(f'StudentKnowledge.start_topic({topic})')
         if self.current_topic == topic:
@@ -88,7 +87,7 @@ class StudentKnowledge(object):
 
         t = self.deps.node[topic]
         k = t['choose']
-        if t['shuffle']:
+        if t['shuffle_questions']:
             questions = random.sample(t['questions'], k=k)
         else:
             questions = t['questions'][:k]
@@ -131,11 +130,10 @@ class StudentKnowledge(object):
         q = self.current_question
         q['answer'] = answer
         q['finish_time'] = datetime.now()
-        grade = await q.correct_async()
-
-        logger.debug(f'Grade {grade:.2} ({q["ref"]})')
+        await q.correct_async()
+        logger.debug(f'Grade {q["grade"]:.2} ({q["ref"]})')
 
-        if grade > 0.999:
+        if q['grade'] > 0.999:
             self.correct_answers += 1
             self.next_question()
             action = 'right'
diff --git a/aprendizations/learnapp.py b/aprendizations/learnapp.py
index dc193b8..2e24338 100644
--- a/aprendizations/learnapp.py
+++ b/aprendizations/learnapp.py
@@ -26,8 +26,7 @@ logger = logging.getLogger(__name__)
 # helper functions
 # ============================================================================
 async def _bcrypt_hash(a, b):
-    # loop = asyncio.get_running_loop()   # FIXME python 3.7 only
-    loop = asyncio.get_event_loop()
+    loop = asyncio.get_running_loop()
     return await loop.run_in_executor(None, bcrypt.hashpw,
                                       a.encode('utf-8'), b)
 
@@ -248,11 +247,12 @@ class LearnApp(object):
 
         # default attributes that apply to the topics
         default_file = config.get('file', 'questions.yaml')
-        default_shuffle = config.get('shuffle', True)
+        default_shuffle_questions = config.get('shuffle_questions', True)
         default_choose = config.get('choose', 9999)
         default_forgetting_factor = config.get('forgetting_factor', 1.0)
         default_maxtries = config.get('max_tries', 3)
         default_append_wrong = config.get('append_wrong', True)
+        default_min_level = config.get('min_level', 0.01)  # to unlock topic
 
         # iterate over topics and populate graph
         topics = config.get('topics', {})
@@ -267,10 +267,11 @@ class LearnApp(object):
             t['name'] = attr.get('name', tref)
             t['path'] = path.join(g.graph['prefix'], tref)    # prefix/topic
             t['file'] = attr.get('file', default_file)        # questions.yaml
-            t['shuffle'] = attr.get('shuffle', default_shuffle)
+            t['shuffle_questions'] = attr.get('shuffle_questions', default_shuffle_questions)
             t['max_tries'] = attr.get('max_tries', default_maxtries)
             t['forgetting_factor'] = attr.get('forgetting_factor',
                                               default_forgetting_factor)
+            t['min_level'] = attr.get('min_level', default_min_level)
             t['choose'] = attr.get('choose', default_choose)
             t['append_wrong'] = attr.get('append_wrong', default_append_wrong)
             t['questions'] = attr.get('questions', [])
diff --git a/aprendizations/questions.py b/aprendizations/questions.py
index 5de9374..0bd37f7 100644
--- a/aprendizations/questions.py
+++ b/aprendizations/questions.py
@@ -43,17 +43,15 @@ class Question(dict):
             'files': {},
             })
 
-    def correct(self) -> float:
+    def correct(self) -> None:
         self['comments'] = ''
         self['grade'] = 0.0
-        return 0.0
 
-    async def correct_async(self) -> float:
-        loop = asyncio.get_running_loop()  # FIXME python 3.7 only
-        # loop = asyncio.get_event_loop()  # python 3.6
-        return await loop.run_in_executor(None, self.correct)
+    async def correct_async(self) -> None:
+        loop = asyncio.get_running_loop()
+        await loop.run_in_executor(None, self.correct)
 
-    def set_defaults(self, d):
+    def set_defaults(self, d) -> None:
         'Add k:v pairs from default dict d for nonexistent keys'
         for k, v in d.items():
             self.setdefault(k, v)
@@ -204,8 +202,6 @@ class QuestionCheckbox(Question):
 
                 self['grade'] = x / sum_abs
 
-        return self['grade']
-
 
 # ===========================================================================
 class QuestionText(Question):
@@ -239,8 +235,6 @@ class QuestionText(Question):
         if self['answer'] is not None:
             self['grade'] = 1.0 if self['answer'] in self['correct'] else 0.0
 
-        return self['grade']
-
 
 # ===========================================================================
 class QuestionTextRegex(Question):
@@ -271,8 +265,6 @@ class QuestionTextRegex(Question):
                              f'answer {self["answer"]}.')
             self['grade'] = 1.0 if ok else 0.0
 
-        return self['grade']
-
 
 # ===========================================================================
 class QuestionNumericInterval(Question):
@@ -308,8 +300,6 @@ class QuestionNumericInterval(Question):
             else:
                 self['grade'] = 1.0 if lower <= answer <= upper else 0.0
 
-        return self['grade']
-
 
 # ===========================================================================
 class QuestionTextArea(Question):
@@ -358,8 +348,6 @@ class QuestionTextArea(Question):
             else:
                 self['grade'] = float(out)
 
-        return self['grade']
-
 
 # ===========================================================================
 class QuestionInformation(Question):
@@ -375,4 +363,3 @@ class QuestionInformation(Question):
     def correct(self):
         super().correct()
         self['grade'] = 1.0  # always "correct" but points should be zero!
-        return self['grade']
diff --git a/aprendizations/serve.py b/aprendizations/serve.py
index 8b04785..cd7a7ec 100644
--- a/aprendizations/serve.py
+++ b/aprendizations/serve.py
@@ -95,7 +95,7 @@ class LoginHandler(BaseHandler):
         self.render('login.html', error='')
 
     async def post(self):
-        uid = self.get_body_argument('uid')
+        uid = self.get_body_argument('uid').lstrip('l')
         pw = self.get_body_argument('pw')
 
         login_ok = await self.learn.login(uid, pw)
diff --git a/aprendizations/static/css/topic.css b/aprendizations/static/css/topic.css
index 90db3ed..01aae8e 100644
--- a/aprendizations/static/css/topic.css
+++ b/aprendizations/static/css/topic.css
@@ -23,6 +23,7 @@ html {
     position: relative;
     min-height: 100%;
 }
-textarea {
-    font-family: monospace;
+.CodeMirror {
+    border: 1px solid #eee;
+    height: auto;
 }
diff --git a/aprendizations/templates/question-textarea.html b/aprendizations/templates/question-textarea.html
index 8a9c435..895dcbf 100644
--- a/aprendizations/templates/question-textarea.html
+++ b/aprendizations/templates/question-textarea.html
@@ -7,10 +7,9 @@
 
 <script>
     var editor = CodeMirror.fromTextArea(document.getElementById("code"), {
-        lineNumbers: true,
-        mode: "clike",
-        // matchBrackets: true,
-        // theme: "night",
+      lineNumbers: true,
+      viewportMargin: Infinity,
+      // styleActiveLine: true,
     });
 </script>
 
diff --git a/aprendizations/templates/topic.html b/aprendizations/templates/topic.html
index 9a47685..911b930 100644
--- a/aprendizations/templates/topic.html
+++ b/aprendizations/templates/topic.html
@@ -32,8 +32,8 @@
   <script defer src="/static/mdbootstrap/js/bootstrap.min.js"></script>
   <script defer src="/static/mdbootstrap/js/mdb.min.js"></script>
   <script defer src="/static/fontawesome-free/js/all.min.js"></script>
-	<script defer src="/static/codemirror/lib/codemirror.js"></script>
-	<script defer src="/static/js/topic.js"></script>
+  <script defer src="/static/codemirror/lib/codemirror.js"></script>
+  <script defer src="/static/js/topic.js"></script>
 
 </head>
 <!-- ===================================================================== -->
diff --git a/aprendizations/tools.py b/aprendizations/tools.py
index 9f10cc5..2d7d727 100644
--- a/aprendizations/tools.py
+++ b/aprendizations/tools.py
@@ -147,7 +147,7 @@ def load_yaml(filename, default=None):
     else:
         with f:
             try:
-                default = yaml.load(f)
+                default = yaml.safe_load(f)  # FIXME check if supports all kinds of questions including regex
             except yaml.YAMLError as e:
                 mark = e.problem_mark
                 logger.error(f'In file "{filename}" near line {mark.line}, '
@@ -187,7 +187,7 @@ def run_script(script, args=[], stdin='', timeout=5):
             logger.error(f'Return code {p.returncode} running "{script}".')
         else:
             try:
-                output = yaml.load(p.stdout)
+                output = yaml.safe_load(p.stdout)
             except Exception:
                 logger.error(f'Error parsing yaml output of "{script}"')
             else:
diff --git a/demo/demo.yaml b/demo/demo.yaml
index 2298e93..ec92143 100644
--- a/demo/demo.yaml
+++ b/demo/demo.yaml
@@ -5,12 +5,13 @@ database: students.db
 
 
 # values applie to each topic, if undefined there
-# default values are: file=question.yaml, shuffle=True, choose: all
 file: questions.yaml
-shuffle: false
+shuffle_questions: true
 choose: 6
 max_tries: 2
-forgetting_factor: 0.99
+forgetting_factor: 0.97
+min_level: 0.01
+append_wrong: true
 
 # ----------------------------------------------------------------------------
 topics:
--
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