widgets: ensure types on class_init

This will avoid GtkBuilder crashing because it couldn't
find the correct type for a given widget.

src/gcal-date-selector.c

@@ -189,6 +189,8 @@ gcal_date_selector_class_init (GcalDateSelectorClass *klass)
   GtkEntryClass *entry_class = GTK_ENTRY_CLASS (klass);
   GObjectClass *object_class = G_OBJECT_CLASS (klass);
 
+  g_type_ensure (GCAL_TYPE_DATE_CHOOSER);
+
   object_class->finalize = gcal_date_selector_finalize;
   object_class->get_property = gcal_date_selector_get_property;
   object_class->set_property = gcal_date_selector_set_property;

src/gcal-edit-dialog.c

@@ -742,6 +742,9 @@ gcal_edit_dialog_class_init (GcalEditDialogClass *klass)
   GObjectClass *object_class = G_OBJECT_CLASS (klass);
   GtkWidgetClass *widget_class = GTK_WIDGET_CLASS (klass);
 
+  g_type_ensure (GCAL_TYPE_DATE_SELECTOR);
+  g_type_ensure (GCAL_TYPE_TIME_SELECTOR);
+
   object_class->finalize = gcal_edit_dialog_finalize;
   object_class->constructed = gcal_edit_dialog_constructed;
   object_class->get_property = gcal_edit_dialog_get_property;

src/gcal-window.c

@@ -1457,11 +1457,19 @@ gcal_window_state_event (GtkWidget           *widget,
 }
 
 static void
-gcal_window_class_init(GcalWindowClass *klass)
+gcal_window_class_init (GcalWindowClass *klass)
 {
   GObjectClass *object_class;
   GtkWidgetClass *widget_class;
 
+  g_type_ensure (GCAL_TYPE_EDIT_DIALOG);
+  g_type_ensure (GCAL_TYPE_MONTH_VIEW);
+  g_type_ensure (GCAL_TYPE_QUICK_ADD_POPOVER);
+  g_type_ensure (GCAL_TYPE_SEARCH_VIEW);
+  g_type_ensure (GCAL_TYPE_SOURCE_DIALOG);
+  g_type_ensure (GCAL_TYPE_WEEK_VIEW);
+  g_type_ensure (GCAL_TYPE_YEAR_VIEW);
+
   object_class = G_OBJECT_CLASS (klass);
   object_class->finalize = gcal_window_finalize;
   object_class->set_property = gcal_window_set_property;

src/views/gcal-week-view.c

@@ -588,6 +588,9 @@ gcal_week_view_class_init (GcalWeekViewClass *klass)
   GObjectClass *object_class = G_OBJECT_CLASS (klass);
   GtkWidgetClass *widget_class = GTK_WIDGET_CLASS (klass);
 
+  g_type_ensure (GCAL_TYPE_WEEK_GRID);
+  g_type_ensure (GCAL_TYPE_WEEK_HEADER);
+
   object_class->finalize = gcal_week_view_finalize;
   object_class->set_property = gcal_week_view_set_property;
   object_class->get_property = gcal_week_view_get_property;