diff --git a/sloth/annotations/model.py b/sloth/annotations/model.py
index 7d194b9..8feaec4 100644
--- a/sloth/annotations/model.py
+++ b/sloth/annotations/model.py
@@ -1,23 +1,25 @@
 """
 The annotationmodel module contains the classes for the AnnotationModel.
 """
-from PyQt4.QtGui import QTreeView, QItemSelection, QItemSelectionModel, QSortFilterProxyModel, QBrush
-from PyQt4.QtCore import QModelIndex, QAbstractItemModel, Qt, pyqtSignal, QVariant
-import os.path, sys
-import copy
-from collections import MutableMapping
+import os.path
 import time
 import logging
+import copy
+from collections import MutableMapping
+from PyQt4.QtGui import QTreeView, QItemSelection, QItemSelectionModel, QSortFilterProxyModel, QBrush
+from PyQt4.QtCore import QModelIndex, QAbstractItemModel, Qt, pyqtSignal, QVariant
+
 LOG = logging.getLogger(__name__)
 
 ItemRole, DataRole, ImageRole = [Qt.UserRole + i + 1 for i in range(3)]
 
+
 class ModelItem:
     def __init__(self):
-        self._loaded    = True
-        self._model     = None
-        self._parent    = None
-        self._row       = -1
+        self._loaded = True
+        self._model = None
+        self._parent = None
+        self._row = -1
         if not hasattr(self, "_children"):
             self._children = []
 
@@ -579,18 +581,21 @@ class KeyValueRowModelItem(ModelItem):
             return True
         return False
 
+
 class AnnotationModel(QAbstractItemModel):
     # signals
     dirtyChanged = pyqtSignal(bool, name='dirtyChanged')
 
     def __init__(self, annotations, parent=None):
         QAbstractItemModel.__init__(self, parent)
+
         start = time.time()
         self._annotations = annotations
-        self._dirty       = False
-        self._root        = RootModelItem(self, annotations)
+        self._dirty = False
+        self._root = RootModelItem(self, annotations)
         diff = time.time() - start
         LOG.info("Created AnnotationModel in %.2fs" % (diff, ))
+
         self.dataChanged.connect(self.onDataChanged)
         self.rowsInserted.connect(self.onDataChanged)
         self.rowsRemoved.connect(self.onDataChanged)
diff --git a/sloth/gui/propertyeditor.py b/sloth/gui/propertyeditor.py
index 6a34a93..c64c729 100644
--- a/sloth/gui/propertyeditor.py
+++ b/sloth/gui/propertyeditor.py
@@ -1,24 +1,31 @@
+import time
+import logging
+from PyQt4.QtCore import pyqtSignal, QSize, Qt
+from PyQt4.QtGui import QWidget, QGroupBox, QVBoxLayout, QPushButton, QScrollArea, QLineEdit, QDoubleValidator, QIntValidator, QShortcut, QKeySequence
 from sloth.core.exceptions import ImproperlyConfigured
 from sloth.annotations.model import AnnotationModelItem
 from sloth.gui.floatinglayout import FloatingLayout
 from sloth.gui.utils import MyVBoxLayout
 from sloth.utils.bind import bind
-from PyQt4.QtCore import pyqtSignal, QSize, Qt
-from PyQt4.QtGui import QWidget, QGroupBox, QVBoxLayout, QPushButton, QScrollArea, QLineEdit, QDoubleValidator, QIntValidator, QShortcut, QKeySequence
-import time
-import logging
+
+
 LOG = logging.getLogger(__name__)
 
+
 class AbstractAttributeHandler:
     def defaults(self):
         return {}
+
     def updateValues(self, values):
         pass
+
     def setItems(self, items, showItemClasses=False):
         pass
+
     def autoAddEnabled(self):
         return False
 
+
 class AttributeHandlerFactory:
     def create(self, attribute, values):
         # Class attribute cannot be changed
@@ -36,17 +43,18 @@ class AttributeHandlerFactory:
         # Else, we create our own default handler
         return DefaultAttributeHandler(attribute, values)
 
+
 class DefaultAttributeHandler(QGroupBox, AbstractAttributeHandler):
     def __init__(self, attribute, values, parent=None):
         QGroupBox.__init__(self, attribute, parent)
-        self._attribute      = attribute
-        self._current_items  = []
-        self._defaults       = {}
-        self._inputField     = None
+        self._attribute = attribute
+        self._current_items = []
+        self._defaults = {}
+        self._inputField = None
         self._inputFieldType = None
-        self._insertIndex    = -1
-        self._insertAtEnd    = False
-        self._shortcuts      = {}
+        self._insertIndex = -1
+        self._insertAtEnd = False
+        self._shortcuts = {}
 
         # Setup GUI
         self._layout = FloatingLayout()
@@ -257,7 +265,8 @@ class LabelEditor(QScrollArea):
             handler = self._editor.getHandler(attr)
             if handler is not None:
                 if len(items) > 1:
-                    valid_items = [item for item in items if attr in self._editor.getLabelClassAttributes(item['class'])]
+                    valid_items = [item for item in items
+                                   if attr in self._editor.getLabelClassAttributes(item['class'])]
                     handler.setItems(valid_items, True)
                 else:
                     handler.setItems(items)
@@ -285,6 +294,7 @@ class LabelEditor(QScrollArea):
     def insertionMode(self):
         return self._insertion_mode
 
+
 class PropertyEditor(QWidget):
     # Signals
     insertionModeStarted       = pyqtSignal(str)