search-view: no show search view if field is empty

When the search field is empty is not needed show the result drop down.

https://bugzilla.gnome.org/show_bug.cgi?id=747962

data/ui/window.ui

@@ -291,7 +291,6 @@
     </child>
   </template>
   <object class="GcalSearchView" id="search_view">
-    <property name="visible" bind-source="search_bar" bind-property="search-mode-enabled" bind-flags="default | sync-create" />
     <property name="relative_to">search_entry</property>
     <property name="position">bottom</property>
     <signal name="event-activated" handler="search_event_selected" object="GcalWindow" swapped="no"/>

src/gcal-window.c

@@ -1197,13 +1197,25 @@ search_changed (GtkEditable *editable,
                 gpointer     user_data)
 {
   GcalWindow *window = GCAL_WINDOW (user_data);
+  gint search_length;
 
   if (gtk_search_bar_get_search_mode (GTK_SEARCH_BAR (window->search_bar)))
     {
-      /* perform the search */
+      /* perform the search or hide when the field is empty */
+
+      search_length = gtk_entry_get_text_length (GTK_ENTRY (window->search_entry));
+
+      if (search_length)
+        {
+          gtk_popover_popup (GTK_POPOVER (window->search_view));
           gcal_search_view_search (GCAL_SEARCH_VIEW (window->search_view),
                                    "summary", gtk_entry_get_text (GTK_ENTRY (window->search_entry)));
         }
+      else
+        {
+          gtk_popover_popdown (GTK_POPOVER (window->search_view));
+        }
+    }
 }
 
 static void