Aligning dialog buttons to center using Python GTK+ 3

I have made a Python application which uses GTK. I want to send the user a dialog asking for confirmation for an action, however after creating the dialog based on this tutorial, I noticed that there is no apparent way to center-align the 'Cancel' and 'OK' buttons.

The relavent code from that tutorial is as follows:

class DialogExample(Gtk.Dialog):
    def __init__(self, parent):
        Gtk.Dialog.__init__(self, "My Dialog", parent, 0,
            (Gtk.STOCK_CANCEL, Gtk.ResponseType.CANCEL,
             Gtk.STOCK_OK, Gtk.ResponseType.OK))
        self.set_default_size(150, 100)
        label = Gtk.Label("This is a dialog to display additional information")
        box = self.get_content_area()
        box.add(label)
        self.show_all()

In the example above, the buttons are aligned to the right. Is there any way to center align the buttons using this method of creating dialogs?

Solution

Question: Aligning dialog buttons to center

You want to center the action_area of a Gtk.Dialog, which is of type Gtk.ButtonBox.
Get the action_area

Note: Deprecated since version 3.12: Direct access to the action area is discouraged
```
a_area = self.get_action_area()
```
You need the parent of the action_area, which is of type Gtk.Box
Get the parent box.
```
box = a_area.props.parent
```
To center a Gtk.Widget you have to reset the default packing expand=False to True.
To all other packing options no change.
```
box.set_child_packing(a_area, True, False, 0, Gtk.PackType.END)
```
Now, you can center the action_area
```
a_area.set_center_widget(None)
```

Output:

Tested with Python: 3.5 - gi.__version__: 3.22.0