How to disable GtkAssistant side bar with Page Title defined?

Question

I'm struggling with a GtkAssistant sidebar that is appearing automatically when I define a page title.

GtkAssistant does not accept Window Title. You need to define a Page Title but it enables that side bar.

I just want the Page Title. An example:

Considering this example, I would like to keep "Error Details" title but hide side bar. It is not useful for me. And there is no Gtk Doc mentions to remove that. Not sure if I can.

A glade example:

<?xml version="1.0" encoding="UTF-8"?>
<!-- Generated with glade 3.22.1 -->
<interface>
  <requires lib="gtk+" version="3.2"/>
  <object class="GtkAssistant" id="assistant">
    <property name="can_focus">False</property>
    <property name="use_header_bar">0</property>
    <signal name="cancel" handler="on_destroy" swapped="no"/>
    <signal name="close" handler="on_destroy" swapped="no"/>
    <signal name="delete-event" handler="on_destroy" swapped="no"/>
    <child>
      <object class="GtkBox" id="page1">
        <property name="visible">True</property>
        <property name="can_focus">False</property>
        <property name="margin_left">7</property>
        <property name="margin_right">7</property>
        <property name="margin_top">7</property>
        <property name="margin_bottom">7</property>
        <property name="orientation">vertical</property>
        <child>
          <object class="GtkLabel">
            <property name="visible">True</property>
            <property name="can_focus">False</property>
            <property name="label" translatable="yes">Name:</property>
          </object>
          <packing>
            <property name="expand">False</property>
            <property name="fill">True</property>
            <property name="position">0</property>
          </packing>
        </child>
        <child>
          <object class="GtkEntry">
            <property name="visible">True</property>
            <property name="can_focus">True</property>
          </object>
          <packing>
            <property name="expand">False</property>
            <property name="fill">True</property>
            <property name="position">1</property>
          </packing>
        </child>
        <child>
          <object class="GtkLabel">
            <property name="visible">True</property>
            <property name="can_focus">False</property>
            <property name="label" translatable="yes">Surname:</property>
          </object>
          <packing>
            <property name="expand">False</property>
            <property name="fill">True</property>
            <property name="position">2</property>
          </packing>
        </child>
        <child>
          <object class="GtkEntry">
            <property name="visible">True</property>
            <property name="can_focus">True</property>
          </object>
          <packing>
            <property name="expand">False</property>
            <property name="fill">True</property>
            <property name="position">3</property>
          </packing>
        </child>
      </object>
      <packing>
        <property name="page_type">intro</property>
        <property name="title" translatable="yes">User Info</property>
        <property name="has_padding">False</property>
      </packing>
    </child>
    <child>
      <object class="GtkBox" id="page2">
        <property name="visible">True</property>
        <property name="can_focus">False</property>
        <property name="margin_left">7</property>
        <property name="margin_right">7</property>
        <property name="margin_top">7</property>
        <property name="margin_bottom">7</property>
        <property name="orientation">vertical</property>
        <child>
          <object class="GtkLabel">
            <property name="visible">True</property>
            <property name="can_focus">False</property>
            <property name="label" translatable="yes">Address:</property>
          </object>
          <packing>
            <property name="expand">False</property>
            <property name="fill">True</property>
            <property name="position">0</property>
          </packing>
        </child>
        <child>
          <object class="GtkEntry">
            <property name="visible">True</property>
            <property name="can_focus">True</property>
          </object>
          <packing>
            <property name="expand">False</property>
            <property name="fill">True</property>
            <property name="position">1</property>
          </packing>
        </child>
        <child>
          <object class="GtkLabel">
            <property name="visible">True</property>
            <property name="can_focus">False</property>
            <property name="label" translatable="yes">Telephone:</property>
          </object>
          <packing>
            <property name="expand">False</property>
            <property name="fill">True</property>
            <property name="position">2</property>
          </packing>
        </child>
        <child>
          <object class="GtkEntry">
            <property name="visible">True</property>
            <property name="can_focus">True</property>
          </object>
          <packing>
            <property name="expand">False</property>
            <property name="fill">True</property>
            <property name="position">3</property>
          </packing>
        </child>
      </object>
      <packing>
        <property name="title" translatable="yes">Extra Info</property>
        <property name="has_padding">False</property>
      </packing>
    </child>
    <child>
      <object class="GtkBox" id="page3">
        <property name="visible">True</property>
        <property name="can_focus">False</property>
        <property name="orientation">vertical</property>
        <child>
          <placeholder/>
        </child>
        <child>
          <object class="GtkLabel">
            <property name="visible">True</property>
            <property name="can_focus">False</property>
            <property name="label" translatable="yes">Thanks for registering!</property>
            <attributes>
              <attribute name="weight" value="bold"/>
              <attribute name="scale" value="1.5"/>
            </attributes>
          </object>
          <packing>
            <property name="expand">False</property>
            <property name="fill">True</property>
            <property name="position">1</property>
          </packing>
        </child>
        <child>
          <placeholder/>
        </child>
      </object>
      <packing>
        <property name="page_type">summary</property>
        <property name="title" translatable="yes">Success</property>
        <property name="has_padding">False</property>
      </packing>
    </child>
    <child>
      <placeholder/>
    </child>
    <child>
      <placeholder/>
    </child>
    <child>
      <placeholder/>
    </child>
    <child>
      <placeholder/>
    </child>
    <child>
      <placeholder/>
    </child>
    <child>
      <placeholder/>
    </child>
    <child>
      <placeholder/>
    </child>
  </object>
</interface>

And the result is:

I would like to remove this weird side bar.

Answer 1

Question: How to disable GtkAssistant side bar with Page Title defined?

Using your glade.xml, i get the following error:

    (Assistant.py:4515): Gtk-CRITICAL **: gtk_assistant_set_page_has_padding: assertion 'child != NULL' failed  

and the    Next    Button keep stay insensitive.

Solved: Using assistant.set_page_complete(box, True) enables the    Next    Button.

---

However, using the following API Reference I get this result:

PyGObject API Reference:

• Gtk.Assistant.signals.prepare
• Gtk.Assistant.set_page_complete
• Gtk.HeaderBar

Drawback:
The OS see the Gtk.Assistant. window title as undefined!
Using GtkAssistant.set_title(... has no result!

---

First add the signal "prepare" using Glade in GtkAssistant.

<signal name="prepare" handler="on_assistant_prepare" swapped="no"/>

Usage:

import gi
gi.require_version('Gtk', '3.0')
from gi.repository import Gtk


class GtkAssistant:
    def __init__(self):
        self.builder = Gtk.Builder()
        self.builder.add_from_file(__file__.replace('.py', '.glade'))
        self.builder.connect_signals(self)

        assistant = self.builder.get_object("assistant")

        # Preserve the page titels from glade
        # Set page titles to empty '' to force not to show sidebar
        for _id in ["page1", "page2", "page3"]:
            box = self.builder.get_object(_id)
            box.page_title = assistant.get_page_title(box)
            assistant.set_page_title(box, '')

        # Gtk.Assistant refuses to do .set_title even defined in glade
        # <property name="title" translatable="yes">Registration-Assistant</property>
        assistant.set_title('Registration-Assistant')

        # Replace assistant.set_page_title(... with own function
        assistant.set_page_title = self.set_page_title

        # Replace the window decoration with a custom HeaderBar
        self.title = Gtk.Label()
        headerbar = Gtk.HeaderBar()
        headerbar.set_show_close_button(True)
        headerbar.set_custom_title(self.title)
        assistant.set_titlebar(headerbar)

        assistant.show_all()

    def set_page_title(self, box, title):
        self.title.set_text(title)

    def on_assistant_prepare(self, assistant, box, user_data=None):
        assistant.set_page_title(box, box.page_title)
        # This will make update the buttons state 
        # to be able to continue the task.
        assistant.set_page_complete(box, True)

    def on_destroy(self, widget, data=None):
        Gtk.main_quit()

if __name__ == '__main__':
    assist = GtkAssistant()
    Gtk.main()

Tested with Python: 3.5 - gi.__version__: 3.22.0 - Glade 3.20.0