Mono spaced font in Glade GtkEntry widget

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I am using Glade to make the form for a GtkEntry widget. I have it properly working in Julia to accept user input from GtkEntry widgets. My question is what setting will make the entered text appear in a mono spaced font? I have searched quite a bit on the Internet with little luck!

Julia code for glade form is below

# note 2022-10-12
# note use Gtk and Glade for gui input

# todo 
# todo method of final completion of form
using Gtk
using Revise
println("Prog has started.")

function my_gui()
    glade = GtkBuilder(filename = "JumpGUI.glade") # XML file created in glade
    window = glade["ArchWindow"]
    a1 = glade["a1"]
    a2 = glade["a2"]
    showall(window)
    str1 = ""
    str2 = ""
    if isinteractive()
        c1 = Condition()
        signal_connect(window, "key-press-event") do widget, event
            if event.keyval == 65293 #Enter
                str1 = get_gtk_property(a1, :text, String)
                str2 = get_gtk_property(a2, :text, String)
                notify(c1)
            end
        end
        wait(c1)
    end
    Gtk.destroy(window)
    return str1, str2
end

s1, s2 = my_gui() # get the GtkEntry input text
@show(s1, s2)

println("Prog has ended.")

Glade xml file

<?xml version="1.0" encoding="UTF-8"?>
<!-- Generated with glade 3.40.0 -->
<interface>
  <requires lib="gtk+" version="3.24"/>
  <object class="GtkWindow" id="ArchWindow">
    <property name="can-focus">False</property>
    <property name="title" translatable="yes">JuMP Window</property>
    <child>
      <object class="GtkBox">
        <property name="visible">True</property>
        <property name="can-focus">False</property>
        <property name="orientation">vertical</property>
        <child>
          <object class="GtkEntry" id="a1">
            <property name="name">a1</property>
            <property name="visible">True</property>
            <property name="can-focus">True</property>
            <property name="width-chars">0</property>
            <property name="max-width-chars">0</property>
            <property name="text" translatable="yes">text1</property>
          </object>
          <packing>
            <property name="expand">False</property>
            <property name="fill">True</property>
            <property name="position">0</property>
          </packing>
        </child>
        <child>
          <object class="GtkEntry" id="a2">
            <property name="visible">True</property>
            <property name="can-focus">True</property>
            <property name="text" translatable="yes">text2</property>
          </object>
          <packing>
            <property name="expand">False</property>
            <property name="fill">True</property>
            <property name="position">1</property>
          </packing>
        </child>
      </object>
    </child>
  </object>
</interface>

Sample of non mono spaced font in the Gui window
image