PyQt5 draggable frameless window

I found an example to set borders on a frameless window, however it's not draggable. How can I make a frameless window draggable? Especially if I can see an example it'll be awesome. Here is my example code(normally the code is longer, that's why there are much libraries just don't mind them);

from PyQt5.QtWidgets import (QMessageBox,QApplication, QWidget, QToolTip, QPushButton,
                             QDesktopWidget, QMainWindow, QAction, qApp, QToolBar, QVBoxLayout,
                             QComboBox,QLabel,QLineEdit,QGridLayout,QMenuBar,QMenu,QStatusBar,
                             QTextEdit,QDialog,QFrame,QProgressBar
                             )
from PyQt5 import QtCore, QtWidgets, QtGui
from PyQt5.QtGui import QIcon,QFont,QPixmap,QPalette
from PyQt5.QtCore import QCoreApplication, Qt,QBasicTimer

import sys

class cssden(QMainWindow):
    def __init__(self):
        super().__init__()


        self.mwidget = QMainWindow(self)
        self.setWindowFlags(QtCore.Qt.FramelessWindowHint)


        #size
        self.setFixedSize(320, 450)
        self.center


        #label
        self.lbl = QLabel(self)
        self.lbl.setText("test")
        self.lbl.setStyleSheet("background-color: rgb(0,0,0);"
                               "border: 1px solid red;"
                               "color: rgb(255,255,255);"
                               "font: bold italic 20pt 'Times New Roman';")
        self.lbl.setGeometry(5,5,60,40)

        self.show()

    #center
    def center(self):
        qr = self.frameGeometry()
        cp = QDesktopWidget().availableGeometry().center()
        qr.moveCenter(cp)
        self.move(qr.topLeft())

app = QApplication(sys.argv)
app.setStyleSheet("QMainWindow{background-color: darkgray;border: 1px solid black}")

ex = cssden()
sys.exit(app.exec_())

You need to handle the mouse events yourself.

We will need to add an event on mousePressEvent, which will keep the place where we last clicked on the window
Then, we will add a mouseMoveEvent, which will calculate the distance between the last clicked point and the current mouse location. We will move the window according to this distance.

This is the fixed code:

from PyQt5.QtWidgets import (QMessageBox,QApplication, QWidget, QToolTip, QPushButton,
                             QDesktopWidget, QMainWindow, QAction, qApp, QToolBar, QVBoxLayout,
                             QComboBox,QLabel,QLineEdit,QGridLayout,QMenuBar,QMenu,QStatusBar,
                             QTextEdit,QDialog,QFrame,QProgressBar
                             )
from PyQt5 import QtCore, QtWidgets, QtGui
from PyQt5.QtGui import QIcon,QFont,QPixmap,QPalette
from PyQt5.QtCore import QCoreApplication, Qt,QBasicTimer, QPoint

import sys

class cssden(QMainWindow):
    def __init__(self):
        super().__init__()


        self.mwidget = QMainWindow(self)
        self.setWindowFlags(QtCore.Qt.FramelessWindowHint)


        #size
        self.setFixedSize(320, 450)
        self.center()


        #label
        self.lbl = QLabel(self)
        self.lbl.setText("test")
        self.lbl.setStyleSheet("background-color: rgb(0,0,0);"
                               "border: 1px solid red;"
                               "color: rgb(255,255,255);"
                               "font: bold italic 20pt 'Times New Roman';")
        self.lbl.setGeometry(5,5,60,40)

        self.oldPos = self.pos()

        self.show()

    #center
    def center(self):
        qr = self.frameGeometry()
        cp = QDesktopWidget().availableGeometry().center()
        qr.moveCenter(cp)
        self.move(qr.topLeft())

    def mousePressEvent(self, event):
        self.oldPos = event.globalPos()

    def mouseMoveEvent(self, event):
        delta = QPoint (event.globalPos() - self.oldPos)
        #print(delta)
        self.move(self.x() + delta.x(), self.y() + delta.y())
        self.oldPos = event.globalPos()

app = QApplication(sys.argv)
app.setStyleSheet("QMainWindow{background-color: darkgray;border: 1px solid black}")

ex = cssden()
sys.exit(app.exec_())