Window floating atop Maya 2017

maya_floating_win.py

from PySide2 import QtWidgets, QtCore


def _maya_main_window():
    """Return Maya's main window"""
    for obj in QtWidgets.qApp.topLevelWidgets():
        if obj.objectName() == 'MayaWindow':
            return obj
    raise RuntimeError('Could not find MayaWindow instance')


class MyWindow(QtWidgets.QMainWindow):
    def __init__(self, parent):
        super(MyWindow, self).__init__(parent)

        self.setWindowTitle('My window')  # Window title
        self.setObjectName('MyWindowObj')  # Window object name
        self.setWindowFlags(QtCore.Qt.Window)  # Window type
        
        # Makes Maya perform magic which makes the window stay
        # on top in OS X and Linux. As an added bonus, it'll
        # make Maya remember the window position
        self.setProperty("saveWindowPref", True)

        # Widgets setup
        self.widget = QtWidgets.QWidget()
        self.layout = QtWidgets.QVBoxLayout()
        self.button = QtWidgets.QPushButton('Yoghurt')
        self.layout.addWidget(self.button)
        self.widget.setLayout(self.layout)
        self.setCentralWidget(self.widget)


window = MyWindow(parent=_maya_main_window())
window.show()

maya_floating_win_alt1.py

from PySide2 import QtWidgets, QtCore
from shiboken2 import wrapInstance
from maya import OpenMayaUI as omui

class MyWindow(QtWidgets.QMainWindow):
    def __init__(self, parent):
        super(MyWindow, self).__init__(parent)

        self.setWindowTitle('My window')  # Window title
        self.setObjectName('MyWindow')  # Window object name
        self.setWindowFlags(QtCore.Qt.Window)  # Window type
        
        # Makes Maya perform magic which makes the window stay
        # on top in OS X and Linux. As an added bonus, it'll
        # make Maya remember the window position
        self.setProperty("saveWindowPref", True)

        # Widgets setup
        self.widget = QtWidgets.QWidget()
        self.layout = QtWidgets.QVBoxLayout()
        self.button = QtWidgets.QPushButton('Yoghurt')
        self.layout.addWidget(self.button)
        self.widget.setLayout(self.layout)
        self.setCentralWidget(self.widget)


mainWindowPtr = omui.MQtUtil.mainWindow()
mainWindow = wrapInstance(long(mainWindowPtr), QtWidgets.QMainWindow)
window = MyWindow(parent=mainWindow)
window.show()

maya_floating_win_alt2.py

from PySide2 import QtWidgets, QtCore
from maya import OpenMayaUI as omui 

class MyWindow(QtWidgets.QMainWindow):
    def __init__(self, parent):
        super(MyWindow, self).__init__()
        
        self.setWindowFlags(QtCore.Qt.WindowStaysOnTopHint)  # Stays on top of *all* windows in the desktop

        self.widget = QtWidgets.QWidget()
        self.layout = QtWidgets.QVBoxLayout()
        self.button = QtWidgets.QPushButton('Yoghurt')
        self.layout.addWidget(self.button)
        self.widget.setLayout(self.layout)
        self.setCentralWidget(self.widget)


window = MyWindow(parent=omui.MQtUtil.mainWindow())
window.show()