Add an automatic help overlay to gtk3-widget-factory

This is just to verify that the resource loading works.
The help overlay still needs to get populated properly.

demos/widget-factory/Makefile.am

@@ -64,6 +64,7 @@ EXTRA_DIST += 				\
 	widget-factory.ui 		\
 	widget-factory.css		\
 	menus.ui 			\
+	help-overlay.ui			\
 	widget-factory.gresource.xml	\
 	data/source.svg			\
 	data/symbolic-source.svg

demos/widget-factory/help-overlay.ui

@@ -0,0 +1,22 @@
+<interface>
+  <object class="GtkShortcutsWindow" id="help_overlay">
+    <child>
+      <object class="GtkShortcutsSection">
+        <property name="visible">1</property>
+        <child>
+          <object class="GtkShortcutsGroup">
+            <property name="visible">1</property>
+            <property name="title">Group</property>
+            <child>
+              <object class="GtkShortcutsShortcut">
+                <property name="visible">1</property>
+                <property name="accelerator">1</property>
+                <property name="title">One</property>
+              </object>
+            </child>
+          </object>
+        </child>
+      </object>
+    </child>
+  </object>
+</interface>

demos/widget-factory/widget-factory.gresource.xml

@@ -9,4 +9,7 @@
   <gresource prefix="/org/gtk/WidgetFactory/gtk">
     <file preprocess="xml-stripblanks">menus.ui</file>
   </gresource>
+  <gresource prefix="/org/gtk/WidgetFactory/gtk">
+    <file preprocess="xml-stripblanks">help-overlay.ui</file>
+  </gresource>
 </gresources>