New Widget Does Not Get Added

[Vipul-Cariappa]

Expected Behavior

A new Label Widget needs to get added.

Current Behavior

New Label Widget does not get added.

Steps to reproduce

from toga import Box, Button, Label, App, MainWindow
from toga.style import Pack
from toga.constants import COLUMN

class BugApp(App):

    def startup(self):
        self.main_window = MainWindow(title=self.name)

        self.label1 = Label('Some Text...')
        self.button1 = Button(label='Add New Label', on_press=self.add_widget)

        self.box = Box(children=[self.label1, self.button1], style=Pack(direction=COLUMN, padding=20))

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

    def add_widget(self, button):
        x = Label("New Label")
        self.box.add(x)
        self.box.refresh()


if __name__ == '__main__':
    app = BugApp('BugApp', 'mybugapp')
    app.main_loop()

Your Environment

• Python Version 3.7

• Operating System and Version

  • macOS - version:
  • Linux - distro: - version:
  • Windows - Windows 10
  • Other - name: - version:

• Toga Version

  • 0.3.0.dev23

• Toga Target

  • android
  • cocoa
  • django
  • gtk
  • iOS
  • tvOS
  • watchOS
  • winforms
  • win32
  • Other (please specify)

[Vipul-Cariappa]

If we replace

self.main_window.content = self.box

with

self.main_window.content = Box(children=[self.box])

it works as expected.

[tut949]

I have reproduced this issue (and the suggested workaround) on winforms. Also, it appears a similar issue exists on Android - although that seems to have another related bug as well. I don't understand the code well enough yet to be confident on an appropriate fix, but I can make it work by changing two lines in Widget.add_child() in toga_android:

By making those changes (in combination with @Vipul-Cariappa 's suggested workaround for winforms), I can get it working on Android.

[freakboy3742]

I believe these issues have been addressed, and are now formally tested with #1834.