[Vala] question Gtk 3 + gstreamer 1.0

[Flavio Danesse <fdanesse gmail com>]

*Hello, I'm back with questions on the list :) *

In my application I have gtk3 interface and streamings player gstreamer 1.0
implemented separately.
Both work correctly separately and jointly work correctly except in the
following case:

The player emits a signal when the bus changes state of reproduction, that
is, when it comes into play mode, pause, stop, etc.. . .
That signal is captured by the gtk interface to update the image of the
play button - stop.

*The problem is that when this happens, everything freezes gnome.*

    private void update_state(string state){

        if (state == "playing"){
            this.image_button.set_from_stock(
                Gtk.Stock.MEDIA_STOP, Gtk.IconSize.BUTTON);
        }
        else{
            this.image_button.set_from_stock(
                Gtk.Stock.MEDIA_PLAY, Gtk.IconSize.BUTTON);
        }
    }

*I would clean the following warning in my application, but not how to do
it:*

/home/flavio/Documentos/JAMediaSuite/UbuntuRadio/vala/UbuntuRadio.vala.c:164:2:
warning: 'gtk_window_set_opacity' is deprecated (declared at
/usr/include/gtk-3.0/gtk/gtkwindow.h:142): Use 'gtk_widget_set_opacity'
instead [-Wdeprecated-declarations]
  gtk_window_set_opacity ((GtkWindow*) self, 0.5);
  ^
/home/flavio/Documentos/JAMediaSuite/UbuntuRadio/vala/UbuntuRadio.vala.c:
In function 'main':
/home/flavio/Documentos/JAMediaSuite/UbuntuRadio/vala/UbuntuRadio.vala.c:377:2:
warning: 'g_type_init' is deprecated (declared at
/usr/include/glib-2.0/gobject/gtype.h:669) [-Wdeprecated-declarations]
  g_type_init ();
  ^