Main.py

import sys

import zc.lockfile
from PyQt5 import QtCore, QtGui
from PyQt5.QtCore import Qt
from PyQt5.QtGui import QPalette, QColor
from PyQt5.QtWidgets import QApplication, QMessageBox

from MainDialog import MainDialog

if __name__ == "__main__":

    app = QApplication(sys.argv)
    app.setWindowIcon(QtGui.QIcon('Icons/icon.png'))

    try:
        lock = zc.lockfile.LockFile('LOCK')
    except zc.lockfile.LockError:
        QMessageBox.warning(None, "Error", "The program is already opened.", QMessageBox.Ok)
        sys.exit(0)

    # Force the style to be the same on all OSs:
    app.setStyle("Fusion")

    # Now use a palette to switch to dark colors:
    palette = QPalette()
    palette.setColor(QPalette.Window, QColor(53, 53, 53))
    palette.setColor(QPalette.WindowText, Qt.white)
    palette.setColor(QPalette.Base, QColor(25, 25, 25))
    palette.setColor(QPalette.AlternateBase, QColor(53, 53, 53))
    palette.setColor(QPalette.ToolTipBase, Qt.white)
    palette.setColor(QPalette.ToolTipText, Qt.white)
    palette.setColor(QPalette.Text, Qt.white)
    palette.setColor(QPalette.Button, QColor(53, 53, 53))
    palette.setColor(QPalette.ButtonText, Qt.white)
    palette.setColor(QPalette.BrightText, Qt.red)
    palette.setColor(QPalette.Link, QColor(42, 130, 218))
    palette.setColor(QPalette.Highlight, QColor(42, 130, 218))
    palette.setColor(QPalette.HighlightedText, Qt.black)
    app.setPalette(palette)

    form = MainDialog()
    form.setWindowFlags(form.windowFlags() | QtCore.Qt.WindowSystemMenuHint | QtCore.Qt.WindowMinMaxButtonsHint)
    form.setWindowTitle("FRAS")

    form.show()
    sys.exit(app.exec_())