calendar-button: Stop spinning when not synchronizing

GtkSpinner queues relayouts even when the stack is not displaying
it, and this causes excessive redrawing. This button design looks
obsolete and should eventually be reworked, but for now, let's
just stop spinning when the spinner is invisible.

Closes https://gitlab.gnome.org/GNOME/gnome-calendar/-/issues/971

src/gui/gcal-calendar-button.c

@@ -31,6 +31,7 @@ struct _GcalCalendarButton
 
   GtkWidget          *calendar_listbox;
   GtkStack           *icon_stack;
+  GtkSpinner         *refreshing_spinner;
 
   GcalContext        *context;
 
@@ -168,16 +169,16 @@ icon_change_timeout_cb (gpointer data)
 {
   GcalCalendarButton *self;
   GcalManager *manager;
+  gboolean synchronizing;
 
   self = GCAL_CALENDAR_BUTTON (data);
   manager = gcal_context_get_manager (self->context);
+  synchronizing = gcal_manager_get_synchronizing (manager);
 
   g_debug ("Updating calendar icon to spinner");
 
-  if (gcal_manager_get_synchronizing (manager))
-    gtk_stack_set_visible_child_name (self->icon_stack, "spinner");
-  else
-    gtk_stack_set_visible_child_name (self->icon_stack, "icon");
+  gtk_stack_set_visible_child_name (self->icon_stack, synchronizing ? "spinner" : "icon");
+  gtk_spinner_set_spinning (self->refreshing_spinner, synchronizing);
 
   self->icon_changed_source_id = 0;
   return G_SOURCE_REMOVE;
@@ -355,6 +356,7 @@ gcal_calendar_button_class_init (GcalCalendarButtonClass *klass)
 
   gtk_widget_class_bind_template_child (widget_class, GcalCalendarButton, calendar_listbox);
   gtk_widget_class_bind_template_child (widget_class, GcalCalendarButton, icon_stack);
+  gtk_widget_class_bind_template_child (widget_class, GcalCalendarButton, refreshing_spinner);
 
   gtk_widget_class_bind_template_callback (widget_class, on_listbox_row_activated_cb);
 }

src/gui/gcal-calendar-button.ui

@@ -38,7 +38,6 @@
                 <property name="name">spinner</property>
                 <property name="child">
                   <object class="GtkSpinner" id="refreshing_spinner">
-                    <property name="spinning">True</property>
                     <property name="tooltip_text" translatable="yes" context="tooltip">Synchronizing remote calendars…</property>
                   </object>
                 </property>