[pyqtgraph] widgets not repainted on osx with second monitor

[RichardL]

Hi, I'm getting the following issue on OSX 10.10 and 10.11, but not on
10.12.

I have a legacy application that uses PyQt4 and PyQtGraph.

If I have a second/external monitor attached to the Mac, as well as using
the integrated monitor of the Mac itself, the widgets on the application
disappear from view when the application is moved into the second screen
(they are replaced by a blank area in the layout).
It's easy enough to restore the widgets, by just clicking on any other
application that happens to be open, e.g. Finder, browser. I guess this
forces a repaint.
It seems to affect only PyQt widgets: PyQtGraph widgets in the application
don't disappear from view.

Below is a small example that exhibits this behaviour.
(It may be necessary to move the application right to the edge of the
second screen, or to move it back to the first screen, in order to see the
behaviour.)
Note that this example does not even use PyQtGraph. But when pyqtgraph is
imported, the behaviour occurs. When the import is commented out, it
doesn't.
It may well be a purely PyQt issue, but it's only triggered by the use of
pyqtgraph. Any suggestions would be great...!

import sys
from PyQt4 import QtGui
import pyqtgraph as pg # Activate this line to break it

class MainWindow(QtGui.QMainWindow):
def __init__(self, parent=None):
super(MainWindow, self).__init__(parent)
central_widget = QtGui.QWidget()
central_layout = QtGui.QGridLayout(central_widget)
self.setCentralWidget(central_widget)
central_layout.addWidget(QtGui.QLabel('BROKEN'), 0, 0, 1, 1)

def main():
app = QtGui.QApplication(sys.argv)
win = MainWindow()
win.show()
sys.exit(app.exec_())

if __name__ == '__main__':
main()

[RichardL]

Should add that I am on Anaconda; created a new environment then executed
conda install pyqt=4
conda install pyqtgraph

Versions:
python: 2.7.15
pyqt: 4.11.4
pyqtgraph: 0.10.0