In particular, the xfce4-mixer package doesn't build (I already filed a 
bug report for that one, but it feels weird to file a bug on netbsd.org, 
when my system isn't NetBSD), and xfce4-session also fails, as follows 
(most other xfce4 packages build just fine):

gcc -pipe  -o .libs/libbalou.so -bundle  .libs/libbalou_la-balou-theme.o 
.libs/libbalou_la-balou.o .libs/libbalou_la-config.o 
.libs/libbalou_la-engine.o .libs/libbalou_la-gnome-uri.o 
-L/Volumes/PKGSRC/pkgsrc/x11/xfce4-session/work/.buildlink/lib 
-L/Volumes/PKGSRC/pkgsrc/x11/xfce4-session/work/.x11-buildlink/lib 
../../libxfsm/.libs/libxfsm-4.2.dylib
/usr/bin/ld: Undefined symbols:
_g_build_filename
_g_free
_g_malloc0
_g_object_unref
_g_path_get_dirname
_g_strconcat
_g_strdup
_g_strdup_printf
_g_strfreev
_g_strsplit
_g_type_check_instance_cast
_gdk_color_equal
_gdk_color_parse
_gdk_draw_line
_gdk_draw_pixbuf
_gdk_draw_rectangle
_gdk_drawable_get_type
_gdk_gc_new
_gdk_gc_set_function
_gdk_gc_set_rgb_fg_color
_gdk_pixbuf_get_from_drawable
_gdk_pixbuf_get_height
_gdk_pixbuf_get_width
_gdk_pixbuf_new_from_file
_gdk_pixbuf_save
_gdk_pixbuf_scale_simple
_gdk_pixmap_new
_gdk_screen_get_default
_gdk_screen_get_root_window
_libintl_dgettext
_xfce_rc_close
_xfce_rc_read_entry
_xfce_rc_set_group
_xfce_rc_simple_open
_xfce_resource_lookup
_xfce_resource_save_location
_g_main_context_iteration
_g_malloc
_g_object_ref
_gdk_cursor_new
_gdk_cursor_unref
_gdk_display_get_n_screens
_gdk_display_get_screen
_gdk_draw_drawable
_gdk_draw_layout
_gdk_drawable_get_colormap
_gdk_flush
_gdk_gc_get_type
_gdk_gc_new_with_values
_gdk_pango_context_get_for_screen
_gdk_rgb_find_color
_gdk_screen_get_monitor_geometry
_gdk_screen_get_n_monitors
_gdk_window_add_filter
_gdk_window_clear_area
_gdk_window_destroy
_gdk_window_new
_gdk_window_raise
_gdk_window_remove_filter
_gdk_window_set_back_pixmap
_gdk_window_show
_gtk_dialog_get_type
_gtk_dialog_run
_gtk_object_get_type
_gtk_widget_destroy
_gtk_widget_show_now
_gtk_widget_size_request
_gtk_window_get_type
_gtk_window_move
_gtk_window_new
_gtk_window_resize
_gtk_window_set_decorated
_gtk_window_set_screen
_gtk_window_set_skip_pager_hint
_gtk_window_set_skip_taskbar_hint
_pango_context_get_metrics
_pango_context_set_font_description
_pango_font_description_free
_pango_font_description_from_string
_pango_font_metrics_get_ascent
_pango_font_metrics_get_descent
_pango_font_metrics_unref
_pango_layout_get_pixel_size
_pango_layout_get_type
_pango_layout_new
_pango_layout_set_text
_g_dataset_id_set_data_full
_g_idle_add
_g_list_length
_g_log
_g_memdup
_g_object_get_data
_g_object_set_data
_g_object_set_data_full
_g_quark_from_string
_g_realloc
_g_return_if_fail_warning
_g_signal_connect_data
_g_snprintf
_g_spawn_sync
_g_strchomp
_g_strchug
_g_type_check_instance_is_a
_gdk_atom_intern
_gdk_pixbuf_get_type
_gdk_property_change
_gdk_property_get
_gtk_box_get_type
_gtk_box_pack_start
_gtk_cell_renderer_pixbuf_new
_gtk_cell_renderer_text_new
_gtk_container_add
_gtk_container_get_type
_gtk_container_set_border_width
_gtk_dialog_new_with_buttons
_gtk_drag_dest_set
_gtk_drag_finish
_gtk_drag_source_set
_gtk_drag_source_set_icon_pixbuf
_gtk_get_current_event_time
_gtk_image_menu_item_get_type
_gtk_image_menu_item_new_with_mnemonic
_gtk_image_menu_item_set_image
_gtk_image_new_from_stock
_gtk_list_store_append
_gtk_list_store_get_type
_gtk_list_store_new
_gtk_list_store_remove
_gtk_list_store_set
_gtk_menu_get_type
_gtk_menu_new
_gtk_menu_popup
_gtk_menu_shell_append
_gtk_menu_shell_get_type
_gtk_scrolled_window_get_type
_gtk_scrolled_window_new
_gtk_scrolled_window_set_policy
_gtk_scrolled_window_set_shadow_type
_gtk_selection_data_set
_gtk_separator_menu_item_new
_gtk_tree_model_get
_gtk_tree_model_get_iter
_gtk_tree_model_get_iter_first
_gtk_tree_model_get_type
_gtk_tree_model_iter_next
_gtk_tree_selection_get_selected
_gtk_tree_selection_get_tree_view
_gtk_tree_selection_get_type
_gtk_tree_selection_select_iter
_gtk_tree_selection_set_mode
_gtk_tree_view_append_column
_gtk_tree_view_column_new
_gtk_tree_view_column_pack_start
_gtk_tree_view_column_set_attributes
_gtk_tree_view_get_model
_gtk_tree_view_get_path_at_pos
_gtk_tree_view_get_selection
_gtk_tree_view_get_type
_gtk_tree_view_new_with_model
_gtk_tree_view_set_headers_visible
_gtk_vbox_new
_gtk_widget_get_toplevel
_gtk_widget_get_type
_gtk_widget_set_sensitive
_gtk_widget_set_size_request
_gtk_widget_show
_gtk_widget_show_all
_xfce_err
_xfce_file_chooser_get_filename
_xfce_file_chooser_new
_xfce_file_chooser_set_current_name
_xfce_framebox_add
_xfce_framebox_get_type
_xfce_framebox_new
_xfce_gethostname
_xfce_resource_match
_g_ascii_table
_g_list_foreach
_g_list_free
_g_list_prepend
_g_list_reverse
collect2: ld returned 1 exit status
gnumake[4]: *** [libbalou.la] Error 1
gnumake[3]: *** [all-recursive] Error 1
gnumake[2]: *** [all-recursive] Error 1
gnumake[1]: *** [all-recursive] Error 1
gnumake: *** [all] Error 2
*** Error code 2

Stop.
bmake: stopped in /Volumes/PKGSRC/pkgsrc/x11/xfce4-session
*** Error code 1

Stop.
bmake: stopped in /Volumes/PKGSRC/pkgsrc/x11/xfce4-session

---

It strongly looks like the build doesn't find some library, but I don't 
know enough about the build system to find out.  My OS is Darwin, so 
maybe it's Mac-specific.

Best regards,
   Ulrich Hobelmann