[fractal] leave_room: Remove child properties

[Daniel Garcia Moreno <danigm src gnome org>]

commit 50baee93573da44f674f028d07b9ef871d4ee632
Author: Christopher Davis <brainblasted disroot org>
Date:   Sat Oct 31 16:06:39 2020 -0700

    leave_room: Remove child properties
    
    Child properties are gone in GTK4.

 fractal-gtk/res/ui/leave_room.ui | 21 +--------------------
 1 file changed, 1 insertion(+), 20 deletions(-)
---
diff --git a/fractal-gtk/res/ui/leave_room.ui b/fractal-gtk/res/ui/leave_room.ui
index be2d3232..29d88ddd 100644
--- a/fractal-gtk/res/ui/leave_room.ui
+++ b/fractal-gtk/res/ui/leave_room.ui
@@ -22,11 +22,10 @@
         <property name="can_focus">False</property>
         <property name="orientation">vertical</property>
         <child internal-child="action_area">
-          <object class="GtkButtonBox">
+          <object class="GtkBox">
             <property name="can_focus">False</property>
             <property name="hexpand">True</property>
             <property name="homogeneous">True</property>
-            <property name="layout_style">expand</property>
             <child>
               <object class="GtkButton" id="leave_room_cancel">
                 <property name="label" translatable="yes">Cancel</property>
@@ -34,11 +33,6 @@
                 <property name="can_focus">True</property>
                 <property name="receives_default">True</property>
               </object>
-              <packing>
-                <property name="expand">True</property>
-                <property name="fill">True</property>
-                <property name="position">1</property>
-              </packing>
             </child>
             <child>
               <object class="GtkButton" id="leave_room_confirm">
@@ -50,24 +44,11 @@
                   <class name="destructive-action"/>
                 </style>
               </object>
-              <packing>
-                <property name="expand">True</property>
-                <property name="fill">True</property>
-                <property name="position">1</property>
-              </packing>
             </child>
           </object>
-          <packing>
-            <property name="expand">True</property>
-            <property name="fill">True</property>
-            <property name="position">0</property>
-          </packing>
         </child>
       </object>
     </child>
-    <child>
-      <placeholder/>
-    </child>
     <style>
       <class name="leave-room"/>
     </style>