[gtk] gtk-demo: Don't call gtk_main_quit

[Matthias Clasen <matthiasc src gnome org>]

commit 55b60f6da90ac279ffb62081144f20f726a9a8ce
Author: Matthias Clasen <mclasen redhat com>
Date:   Fri Feb 7 16:25:02 2020 -0500

    gtk-demo: Don't call gtk_main_quit
    
    It doesn't work with GtkApplications that do not
    call gtk_main().

 demos/gtk-demo/main.ui | 1 -
 1 file changed, 1 deletion(-)
---
diff --git a/demos/gtk-demo/main.ui b/demos/gtk-demo/main.ui
index bf70a37be6..f4849a6a08 100644
--- a/demos/gtk-demo/main.ui
+++ b/demos/gtk-demo/main.ui
@@ -28,7 +28,6 @@
     <property name="default-width">800</property>
     <property name="default-height">600</property>
     <property name="title">GTK Demo</property>
-    <signal name="destroy" handler="gtk_main_quit" swapped="no"/>
     <child type="titlebar">
       <object class="GtkHeaderBar" id="headerbar">
         <property name="show-title-buttons">1</property>