test_progressbar_box.py

import toga
from colosseum import CSS

class StartApp(toga.App):
    def startup(self):
        self.main_window = toga.MainWindow(self.name)
        self.main_window.app = self

        main_content = toga.Box(style=CSS(flex_direction='row'))

        bar = toga.ProgressBar()
        label = toga.Label('Bar')

        main_content.add(label)
        main_content.add(bar)

        self.main_window.content = main_content
        self.main_window.show()

def main():
    app = StartApp('ProgressBar Test', 'org.pybee.test')
    app.main_loop()

if __name__ == '__main__':
    main()