Only expand shortcut options in StaticConfig objects. This way we can keep a default extruder value in the parts panel

lib/Slic3r/GUI/Plater.pm

@@ -408,6 +408,7 @@ sub load_model_objects {
             $o->add_instance(offset => [ @{$self->{config}->print_center} ]);
         }
     
+        $self->{print}->auto_assign_extruders($o);
         $self->{print}->add_model_object($o);
     }
     

lib/Slic3r/GUI/SkeinPanel.pm

@@ -392,7 +392,7 @@ sub config {
                 $filament_config = $config;
                 next;
             }
-            foreach my $opt_key (keys %$config) {
+            foreach my $opt_key (@{$config->get_keys}) {
                 next unless ref $filament_config->get($opt_key) eq 'ARRAY';
                 push @{ $filament_config->get($opt_key) }, $config->get($opt_key)->[0];
             }