#include <QApplication>
#include <QWidget>
#include <QVBoxLayout>
#include <QPushButton>
#include <QMainWindow>
#pragma push_macro("slots")
#undef slots
#include "Python.h"
#pragma pop_macro("slots")

int main(int argc, char *argv[])
{
    PyObject *pName, *pModule, *pDict, *pFunc;


    // Initialize QApplication and setup basic widgets.
    QApplication app (argc, argv);
    QMainWindow mainWindow (nullptr);
    QPushButton button ("test", &mainWindow);
    QWidget * widget = new QWidget(&mainWindow);
    mainWindow.setCentralWidget(widget);
    auto l = new QVBoxLayout ();
    widget->setLayout(l);
    l->addWidget(&button);

    // Initialize the Python Interpreter
    Py_Initialize();


    // Build the name object
    pName = PyUnicode_FromString("runPyQt");

    // Load the module object
    pModule = PyImport_Import(pName);

    if (!pModule){
        Py_Finalize();
        return 1;
    }

    pDict = PyModule_GetDict(pModule);

    pFunc = PyDict_GetItemString(pDict, "main");

    if (PyCallable_Check(pFunc))
    {
        PyObject_CallObject(pFunc, nullptr);
    } else
    {
        PyErr_Print();
    }

    mainWindow.show();

    int r = 0;

    r = QApplication::exec();

    // Clean up
    Py_DECREF(pModule);
    Py_DECREF(pName);

    // Finish the Python Interpreter
    Py_Finalize();

    return r;
}

import sys
if sys.platform.startswith( 'linux' ) :
    from OpenGL import GL

from PyQt5.QtWidgets import QApplication, QPushButton, QMainWindow



def main():
    app = QApplication.instance()
    widgets = app.topLevelWidgets()
    for widget in widgets:
        if type(widget) is QMainWindow:
            break
    widget = widget.centralWidget()

    widget.layout().addWidget(QPushButton('Hello from PyQt'))