Crash when scroll on figure

[Goczilla]

Bug report

Bug summary

When I use the scroll of the mouse (even without mpl_connect("scroll_event")), the GUI crash. I want to modify the scroll_event function to zoom/dezoom. I already did this in my previous GUI in which it works well.
BUT, no crash with the minimalist example:

import matplotlib.pyplot as plt
plt.figure()
plt.show()

This example is from my real GUI in which I promote a widget in QtDesigner as MPL_Widget_solo.

Code for reproduction

from PyQt5.QtCore import *
from PyQt5.QtWidgets import *
import sys
from matplotlib.backends.backend_qt4agg import FigureCanvasQTAgg as FigureCanvas
from matplotlib.figure import Figure

class MyMplCanvas(FigureCanvas):
    def __init__(self, parent=None):
        self.fig = Figure()
        FigureCanvas.__init__(self, self.fig)
        FigureCanvas.setSizePolicy(self,
                                   QSizePolicy.Expanding,
                                   QSizePolicy.Expanding)
        FigureCanvas.updateGeometry(self)

class MPL_Widget_solo(QWidget):
    def __init__(self, parent = None):
        QWidget.__init__(self, parent)
        self.canvas = MyMplCanvas()
        self.vbox = QVBoxLayout()
        self.vbox.addWidget(self.canvas)
        self.setLayout(self.vbox)

class Ui_Form(object):
    def setupUi(self, Form):
        self.gridLayout = QGridLayout(Form)
        self.widget = MPL_Widget_solo(Form)
        self.gridLayout.addWidget(self.widget, 0, 0, 1, 1)

class Plot_Widget(QWidget, Ui_Form):
    def __init__(self, parent=None):
        super(Plot_Widget, self).__init__(parent)
        self.setupUi(self)

if __name__ == "__main__":
    app = QApplication(sys.argv)
    plot = Plot_Widget()
    plot.show()
    sys.exit(app.exec_())

Actual outcome

`Process finished with exit code 1`

Expected outcome

I wish to modify the scroll event to zoom/dezoom (already done in other GUI in which it works).

Matplotlib version

• Operating system: windows 7 Pro
• Matplotlib version: 2.1.0 (installed via anaconda)
• Matplotlib backend: Qt5Agg
• Python version: 3.6
• Other libraries: PyQt5

[tacaswell]

I think the problem is from matplotlib.backends.backend_qt4agg import FigureCanvasQTAgg as FigureCanvas which should be

from matplotlib.backends.backend_qt5agg import FigureCanvasQTAgg as FigureCanvas

to use the classes which use the correct multiple inheritance super class calling mechanism.