[Vala] vala + gtk+-3.0 ?

[san hoi <hoisan49 gmail com>]

vala : 0.10.7
os : fedora 15

I try to compile customwidget sample in gtk+-3.0. (
http://live.gnome.org/Vala/CustomWidgetSamples#Subclassing_Gtk.Widget
)
but it cannot work.

$ valac --pkg gtk+-3.0 widget.vala
widget.vala:26.5-26.37: error: ValaWidget.size_request: no suitable
method found to override
    public override void size_request (out Gtk.Requisition requisition) {
    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
widget.vala:61.22-61.36: error: The name `WindowClass' does not exist
in the context of `Gdk'
            wclass = Gdk.WindowClass.INPUT_OUTPUT,
                     ^^^^^^^^^^^^^^^
widget.vala:61.13-61.49: error: Invalid type for member `wclass'
            wclass = Gdk.WindowClass.INPUT_OUTPUT,
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
widget.vala:64.9-64.19: error: The name `window' does not exist in the
context of `ValaWidget'
        this.window = new Gdk.Window (get_parent_window (), attrs, 0);
        ^^^^^^^^^^^
widget.vala:65.9-65.19: error: The name `window' does not exist in the
context of `ValaWidget'
        this.window.move_resize (this.allocation.x, this.allocation.y,
        ^^^^^^^^^^^
widget.vala:70.9-70.19: error: The name `window' does not exist in the
context of `ValaWidget'
        this.window.set_user_data (this);
        ^^^^^^^^^^^
widget.vala:74.41-74.51: error: The name `window' does not exist in
the context of `ValaWidget'
        this.style = this.style.attach (this.window);
                                        ^^^^^^^^^^^
widget.vala:78.36-78.46: error: The name `window' does not exist in
the context of `ValaWidget'
        this.style.set_background (this.window, Gtk.StateType.NORMAL);
                                   ^^^^^^^^^^^
widget.vala:81.9-81.17: error: The name `set_flags' does not exist in
the context of `ValaWidget.realize'
        set_flags (WidgetFlags.REALIZED);
        ^^^^^^^^^
widget.vala:92.36-92.46: error: The name `window' does not exist in
the context of `ValaWidget'
        var cr = Gdk.cairo_create (this.window);
                                   ^^^^^^^^^^^
widget.vala:95.55-95.64: error: The name `state' does not exist in the
context of `ValaWidget'
        Gdk.cairo_set_source_color (cr, this.style.fg[this.state]);
                                                      ^^^^^^^^^^
widget.vala:97.23-97.37: error: The name `allocation' does not exist
in the context of `ValaWidget'
                      this.allocation.width - 2 * BORDER_WIDTH,
                      ^^^^^^^^^^^^^^^
widget.vala:98.23-98.37: error: The name `allocation' does not exist
in the context of `ValaWidget'
                      this.allocation.height - 2 * BORDER_WIDTH);
                      ^^^^^^^^^^^^^^^
widget.vala:106.22-106.36: error: The name `allocation' does not exist
in the context of `ValaWidget'
        cr.move_to ((this.allocation.width - fontw) / 2,
                     ^^^^^^^^^^^^^^^
widget.vala:107.22-107.36: error: The name `allocation' does not exist
in the context of `ValaWidget'
                    (this.allocation.height - fonth) / 2);
                     ^^^^^^^^^^^^^^^
widget.vala:90.5-90.37: error: ValaWidget.expose_event: no suitable
method found to override
    public override bool expose_event (Gdk.EventExpose event) {
    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Compilation failed: 16 error(s), 0 warning(s)

Is there vala's tutorial page for gtk+-3.0? And  is this bug in
gtk+-3.0.vapi binding?
Thank you in advance for any help.