custom_bin
Description:
The custom area to add custom widgets.
This bin can be used to add any custom widget to the message area such as a Gtk.ComboBox or Gtk.CheckButton.
When adding a custom widget to the custom bin, the Granite.MessageDialog.secondary_label's bottom margin will be expanded automatically to compensate for the additional widget in the dialog. Removing the previously added widget will remove the bottom margin.
If you don't want to have any margin between your custom widget and the
Granite.MessageDialog.secondary_label, simply add your
custom widget and then set the Gtk.Label.margin_bottom of
Granite.MessageDialog.secondary_label to 0.