[goobox] extract button: added a tooltip

[Paolo Bacchilega <paobac src gnome org>]

commit e7993a4bf8e879cc8fe8897021517951edd614a4
Author: Paolo Bacchilega <paobac src gnome org>
Date:   Sat Dec 29 12:56:54 2018 +0100

    extract button: added a tooltip

 src/goo-window.c | 1 +
 1 file changed, 1 insertion(+)
---
diff --git a/src/goo-window.c b/src/goo-window.c
index 7ddc88f..6bb0f01 100644
--- a/src/goo-window.c
+++ b/src/goo-window.c
@@ -2345,6 +2345,7 @@ goo_window_construct (GooWindow    *window,
                GtkWidget *button;
 
                button = _gtk_image_button_new_for_header_bar (GOO_ICON_NAME_EXTRACT);
+               gtk_widget_set_tooltip_text (button, _("Extract Tracks"));
                gtk_actionable_set_action_name (GTK_ACTIONABLE (button), "win.extract");
                gtk_widget_show_all (button);
                gtk_header_bar_pack_end (GTK_HEADER_BAR (headerbar), button);