Support to Qt5.9

[rgcarrasqueira]

Hi!

I've made some adjustments to support Qt5.9

[ghost]

This fails if both PyQt4 and PyQt4 are available bu only PyQt5.QtWebEngineWidgets is unavailable (I guess it's only available in 5.9?):

> python
Python 2.7.13 (default, Mar 22 2017, 12:31:17) [GCC] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> from PyQt5.QtCore import *
>>> from PyQt4.QtCore import *
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
RuntimeError: the PyQt4.QtCore and PyQt5.QtCore modules both wrap the QObject class

[Cybso]

Additionally, QtWebKit is available for PyQt5, too (however, I don't know if it has been marked as deprecated). I would suggest to use find_spec from importlib to validate the dependencies instead of try..except:

if importlib.util.find_spec("PyQt5") is None:
    import PyQt4...
else:
    import PyQt5...
    if importlib.util.find_spec("PyQt5.QtWebEngineWidgets") is None:
        import PyQt5.QtWebKit
    else:
        import PyQt5.QtWebEngine

(Edit: Sorry, using find_spec would break Python 2.x support)

[rgcarrasqueira]

Yeah! The Problem is the qt developer changed a lot of things on calling some libraries and methods, for example WebPage was changed to WebPageEngine and it messed up everything.

[Cybso]

The easiest solution would be to move the import of QtWebEngine into the first line and only support QtWebKit for Qt4 and QtWebEngine for Qt5.