[GTKUI] Replace decode_string with decode(utf-8)

* We know that GTK widgets will return utf-8 encoded so no need to decode_string.

deluge/ui/gtkui/listview.py

@@ -13,7 +13,6 @@ import gtk
 from gobject import SIGNAL_RUN_LAST, TYPE_NONE, signal_new
 from gtk.gdk import Event  # pylint: disable=ungrouped-imports
 
-from deluge.common import decode_string
 from deluge.ui.gtkui.common import load_pickled_state_file, save_pickled_state_file
 
 signal_new('button-press-event', gtk.TreeViewColumn, SIGNAL_RUN_LAST, TYPE_NONE, (Event,))
@@ -531,7 +530,7 @@ class ListView(object):
         column_in_state = False
         if self.state is not None:
             for column_state in self.state:
-                if header == decode_string(column_state.name):
+                if header == column_state.name.decode('utf-8'):
                     # We found a loaded state
                     column_in_state = True
                     if column_state.width > 0: