rem: hide_prefs (GtkWidget *playlist, int trash, gpointer user_data)
add: hide_prefs (GtkWidget *widget, int trash, gpointer user_data)
context: hide_prefs (GtkWidget *playlist, int trash, gpointer user_data){	Totem *totem = (Totem *)user_data;	gtk_widget_hide (totem->prefs);}