Gtk.Box doesn't update in subclass of Gtk.Bin (PyGObject)

Platform
1

Minimal reproducible example:

import gi
gi.require_version("Gtk", "3.0")
gi.require_version("GLib", "2.0")
from gi.repository import Gtk, GLib

class Test(Gtk.Bin):
    def __init__(self):
         super().__init__()
         box = Gtk.Box()
         self.add(box)

         GLib.timeout_add(lambda _: box.add(Gtk.Button.new_with_label("you will not see me")), 100)

window = Gtk.Window(title="Hello World")
test = Test()
window.add(test)
window.show_all()
window.connect("destroy", Gtk.main_quit)
Gtk.main()

the button is never shown. the box remains empty visually

2

You never show the children of Test. You never show Test either, to be fair.

Widgets, in GTK3, are hidden by default; you need to explicitly show them by calling show(), or recursively show them by calling show_all() on one of their ancestor.

Try replacing:

window.show()

with:

window.show_all()

and you should see the child widgets appear. Except for the button you add in a timeout: for that you will need to call show() explicitly, as it’s added after the show_all() call returns.

3

the code for test is literally inside the example
class Test(Gtk.Bin):

also, is there a reason I can’t call show_all() again on the parent? would this break things?

4

When I wrote “you never show the children of Test” I literally meant: you need to call show() on every child you add, otherwise it won’t be visible.

ETA: Your timeout_add() function is also wrong, the interval is the first argument, not the last.

Once you explicitly show the widgets, everything works as it should:

import gi
gi.require_version("Gtk", "3.0")
gi.require_version("GLib", "2.0")
from gi.repository import Gtk, GLib

class Test(Gtk.Bin):
    def __init__(self):
        super().__init__()

        # Add a box, and show it
        box = Gtk.Box()
        self.add(box)
        box.show()

        def on_timeout():
            # Add a button, and show it
            button = Gtk.Button.new_with_label("you will not see me")
            box.add(button)
            button.show()
            return GLib.SOURCE_REMOVE

        GLib.timeout_add(100, on_timeout)

window = Gtk.Window(title="Hello World")
window.connect("destroy", Gtk.main_quit)

# Add the Test widget, and show it
test = Test()
window.add(test)
test.show()

# Just show the window
window.show()

Gtk.main()
1 Like
5

You can call show_all() as many times as you want, but you typically want to control which widgets you wish to show, not perform a blanket “please show every single widget in this branch of the widget tree”. For instance, you could have multiple widgets added to a container, and then show/hide them depending on some state; if you call show_all() every time you add a widget, you’ll end up showing everything that’s currently hidden on purpose.

6

i just have a list of things that rerenders. should I just use show_all()? because i need to make them all visible every time

7

You’re making it much more complicated than it necessarily is.

You don’t need to constantly set a widget visible: once a widget is marked as visible with show(), it stays visible until you call hide().

Call show() every time you add a widget to a parent container—or, if you’re using a UI description XML file and GtkBuilder, add a <property name="visible>True</property> element.

8

Every time I update it, all elements are deleted and new elements are added, like rerendering it. Can I just call show_all() on every rerender?

9

Is there some sort of language barrier, here? Should I explain again what I wrote?

You can call show() on every widget you add; you can also call show_all() on their ancestor. The important thing is that you must make a widget visible after adding it to a parent.

10

ok i see. so it is ok to call show_all if the entire list is hidden and must be shown?

11

I don’t know how many more times I can answer the same question in the same way.

At this point, I encourage you to:

1 Like
12

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