diff --git a/GraphicsScene/GraphicsScene.py b/GraphicsScene/GraphicsScene.py
index c80e97e5..73867059 100644
--- a/GraphicsScene/GraphicsScene.py
+++ b/GraphicsScene/GraphicsScene.py
@@ -13,10 +13,13 @@ from .mouseEvents import *
 import pyqtgraph.debug as debug
 from . import exportDialog
 
-try:
-    import sip
-    HAVE_SIP = True
-except:
+if hasattr(QtCore, 'PYQT_VERSION'):
+    try:
+        import sip
+        HAVE_SIP = True
+    except ImportError:
+        HAVE_SIP = False
+else:
     HAVE_SIP = False
 
 
diff --git a/__init__.py b/__init__.py
index 4c768a54..51a0fe5c 100644
--- a/__init__.py
+++ b/__init__.py
@@ -193,7 +193,10 @@ show = image  ## for backward compatibility
     
 def mkQApp():
     global QAPP
-    if QtGui.QApplication.instance() is None:
+    inst = QtGui.QApplication.instance()
+    if inst is None:
         QAPP = QtGui.QApplication([])
+    else:
+        QAPP = inst
     return QAPP
         
diff --git a/graphicsItems/GraphicsItem.py b/graphicsItems/GraphicsItem.py
index 0d0491f1..ba4858cf 100644
--- a/graphicsItems/GraphicsItem.py
+++ b/graphicsItems/GraphicsItem.py
@@ -76,7 +76,7 @@ class GraphicsItem(object):
             if view is None:
                 return None
             viewportTransform = view.viewportTransform()
-        dt = QtGui.QGraphicsObject.deviceTransform(self, viewportTransform)
+        dt = self._qtBaseClass.deviceTransform(self, viewportTransform)
         
         #xmag = abs(dt.m11())+abs(dt.m12())
         #ymag = abs(dt.m21())+abs(dt.m22())
@@ -274,19 +274,26 @@ class GraphicsItem(object):
         return vt.mapRect(obj)
 
     def pos(self):
-        return Point(QtGui.QGraphicsObject.pos(self))
+        return Point(self._qtBaseClass.pos(self))
     
     def viewPos(self):
         return self.mapToView(self.mapFromParent(self.pos()))
     
     def parentItem(self):
         ## PyQt bug -- some items are returned incorrectly.
-        return GraphicsScene.translateGraphicsItem(QtGui.QGraphicsObject.parentItem(self))
+        return GraphicsScene.translateGraphicsItem(self._qtBaseClass.parentItem(self))
         
+    def setParentItem(self, parent):
+        ## Workaround for Qt bug: https://bugreports.qt-project.org/browse/QTBUG-18616
+        if parent is not None:
+            pscene = parent.scene()
+            if pscene is not None and self.scene() is not pscene:
+                pscene.addItem(self)
+        return self._qtBaseClass.setParentItem(self, parent)
     
     def childItems(self):
         ## PyQt bug -- some child items are returned incorrectly.
-        return list(map(GraphicsScene.translateGraphicsItem, QtGui.QGraphicsObject.childItems(self)))
+        return list(map(GraphicsScene.translateGraphicsItem, self._qtBaseClass.childItems(self)))
 
 
     def sceneTransform(self):
@@ -296,7 +303,7 @@ class GraphicsItem(object):
         if self.scene() is None:
             return self.transform()
         else:
-            return QtGui.QGraphicsObject.sceneTransform(self)
+            return self._qtBaseClass.sceneTransform(self)
 
 
     def transformAngle(self, relativeItem=None):
@@ -315,7 +322,7 @@ class GraphicsItem(object):
         
         
     #def itemChange(self, change, value):
-        #ret = QtGui.QGraphicsObject.itemChange(self, change, value)
+        #ret = self._qtBaseClass.itemChange(self, change, value)
         #if change == self.ItemParentHasChanged or change == self.ItemSceneHasChanged:
             #print "Item scene changed:", self
             #self.setChildScene(self)  ## This is bizarre.
diff --git a/graphicsItems/GraphicsObject.py b/graphicsItems/GraphicsObject.py
index 91354cfb..f893d8dc 100644
--- a/graphicsItems/GraphicsObject.py
+++ b/graphicsItems/GraphicsObject.py
@@ -8,6 +8,7 @@ class GraphicsObject(GraphicsItem, QtGui.QGraphicsObject):
 
     Extension of QGraphicsObject with some useful methods (provided by :class:`GraphicsItem <pyqtgraph.graphicsItems.GraphicsItem>`)
     """
+    _qtBaseClass = QtGui.QGraphicsObject
     def __init__(self, *args):
         QtGui.QGraphicsObject.__init__(self, *args)
         GraphicsItem.__init__(self)
@@ -17,13 +18,3 @@ class GraphicsObject(GraphicsItem, QtGui.QGraphicsObject):
         if change in [self.ItemParentHasChanged, self.ItemSceneHasChanged]:
             self._updateView()
         return ret
-
-        
-
-    def setParentItem(self, parent):
-        ## Workaround for Qt bug: https://bugreports.qt-project.org/browse/QTBUG-18616
-        if parent is not None:
-            pscene = parent.scene()
-            if pscene is not None and self.scene() is not pscene:
-                pscene.addItem(self)
-        return QtGui.QGraphicsObject.setParentItem(self, parent)
diff --git a/graphicsItems/GraphicsWidget.py b/graphicsItems/GraphicsWidget.py
index c131a54a..8f28d208 100644
--- a/graphicsItems/GraphicsWidget.py
+++ b/graphicsItems/GraphicsWidget.py
@@ -5,6 +5,8 @@ from .GraphicsItem import GraphicsItem
 __all__ = ['GraphicsWidget']
 
 class GraphicsWidget(GraphicsItem, QtGui.QGraphicsWidget):
+    
+    _qtBaseClass = QtGui.QGraphicsWidget
     def __init__(self, *args, **kargs):
         """
         **Bases:** :class:`GraphicsItem <pyqtgraph.GraphicsItem>`, :class:`QtGui.QGraphicsWidget`
@@ -14,7 +16,9 @@ class GraphicsWidget(GraphicsItem, QtGui.QGraphicsWidget):
         """
         QtGui.QGraphicsWidget.__init__(self, *args, **kargs)
         GraphicsItem.__init__(self)
-        GraphicsScene.registerObject(self)  ## workaround for pyqt bug in graphicsscene.items()
+        
+        ## done by GraphicsItem init
+        #GraphicsScene.registerObject(self)  ## workaround for pyqt bug in graphicsscene.items()
 
 ## Removed because this causes segmentation faults. Don't know why.
 #    def itemChange(self, change, value):
@@ -52,11 +56,3 @@ class GraphicsWidget(GraphicsItem, QtGui.QGraphicsWidget):
         return p
 
 
-
-    def setParentItem(self, parent):
-        ## Workaround for Qt bug: https://bugreports.qt-project.org/browse/QTBUG-18616
-        if parent is not None:
-            pscene = parent.scene()
-            if pscene is not None and self.scene() is not pscene:
-                pscene.addItem(self)
-        return QtGui.QGraphicsObject.setParentItem(self, parent)