remove calls to setGraphicsSystem

in fact all are no-ops

examples/PlotAutoRange.py

@@ -11,7 +11,6 @@ from pyqtgraph.Qt import QtGui, QtCore
 import numpy as np
 import pyqtgraph as pg
 
-#QtGui.QApplication.setGraphicsSystem('raster')
 app = pg.mkQApp("Plot Auto Range Example")
 #mw = QtGui.QMainWindow()
 #mw.resize(800,800)

examples/PlotWidget.py

@@ -12,7 +12,6 @@ from pyqtgraph.Qt import QtGui, QtCore
 import numpy as np
 import pyqtgraph as pg
 
-#QtGui.QApplication.setGraphicsSystem('raster')
 app = pg.mkQApp()
 mw = QtGui.QMainWindow()
 mw.setWindowTitle('pyqtgraph example: PlotWidget')

examples/Plotting.py

@@ -12,7 +12,6 @@ from pyqtgraph.Qt import QtGui, QtCore
 import numpy as np
 import pyqtgraph as pg
 
-#QtGui.QApplication.setGraphicsSystem('raster')
 app = pg.mkQApp("Plotting Example")
 #mw = QtGui.QMainWindow()
 #mw.resize(800,800)

examples/VideoSpeedTest.py

@@ -40,7 +40,6 @@ parser.add_argument('--lut-alpha', default=False, action='store_true', help="Use
 parser.add_argument('--size', default='512x512', type=lambda s: tuple([int(x) for x in s.split('x')]), help="WxH image dimensions default='512x512'")
 args = parser.parse_args(sys.argv[1:])
 
-#QtGui.QApplication.setGraphicsSystem('raster')
 app = pg.mkQApp("Video Speed Test Example")
 
 win = QtGui.QMainWindow()

examples/linkedViews.py

@@ -12,7 +12,6 @@ from pyqtgraph.Qt import QtGui, QtCore
 import numpy as np
 import pyqtgraph as pg
 
-#QtGui.QApplication.setGraphicsSystem('raster')
 app = pg.mkQApp("Linked Views Example")
 #mw = QtGui.QMainWindow()
 #mw.resize(800,800)

examples/test_examples.py

@@ -199,7 +199,7 @@ conditionalExamples = {
         )
     ]
 )
-def testExamples(frontend, f, graphicsSystem=None):
+def testExamples(frontend, f):
     # runExampleFile(f[0], f[1], sys.executable, frontend)
 
     name, file = f
@@ -210,15 +210,11 @@ def testExamples(frontend, f, graphicsSystem=None):
     sys.stdout.flush()
     import1 = "import %s" % frontend if frontend != '' else ''
     import2 = os.path.splitext(os.path.split(fn)[1])[0]
-    graphicsSystem = (
-        '' if graphicsSystem is None else  "pg.QtGui.QApplication.setGraphicsSystem('%s')" % graphicsSystem
-    )
     code = """
 try:
     %s
     import initExample
     import pyqtgraph as pg
-    %s
     import %s
     import sys
     print("test complete")
@@ -231,7 +227,7 @@ except:
     print("test failed")
     raise
 
-""" % (import1, graphicsSystem, import2)
+""" % (import1, import2)
     if sys.platform.startswith('win'):
         process = subprocess.Popen([sys.executable],
                                     stdin=subprocess.PIPE,

pyqtgraph/__init__.py

@@ -37,9 +37,7 @@ if 'linux' in sys.platform:  ## linux has numerous bugs in opengl implementation
 elif 'darwin' in sys.platform: ## openGL can have a major impact on mac, but also has serious bugs
     useOpenGL = False
     if QtGui.QApplication.instance() is not None:
-        print('Warning: QApplication was created before pyqtgraph was imported; there may be problems (to avoid bugs, call QApplication.setGraphicsSystem("raster") before the QApplication is created).')
-    if QtGui.QApplication.setGraphicsSystem:
-        QtGui.QApplication.setGraphicsSystem('raster')  ## work around a variety of bugs in the native graphics system 
+        print('Warning: QApplication was created before pyqtgraph was imported; there may be problems.')
 else:
     useOpenGL = False  ## on windows there's a more even performance / bugginess tradeoff.