Don't deactivate no_perimeter_unsupported_algo with arachne, it works.

#4324

src/slic3r/GUI/ConfigManipulation.cpp

@@ -355,10 +355,11 @@ void ConfigManipulation::toggle_print_fff_options(DynamicPrintConfig* config)
 
     toggle_field("perimeter_bonding", config->opt_bool("external_perimeters_first") && !have_arachne && config->option("perimeter_overlap")->get_float() == 100.f && config->option("external_perimeter_overlap")->get_float() == 100.f);
 
-    for (auto el : {"perimeter_loop", "extra_perimeters_overhangs", "no_perimeter_unsupported_algo",
+    for (auto el : {"perimeter_loop", "extra_perimeters_overhangs",
         "thin_perimeters", "perimeter_round_corners"})
         toggle_field(el, have_perimeters && !have_arachne);
-
+
+    toggle_field("no_perimeter_unsupported_algo", have_perimeters);
     toggle_field("only_one_perimeter_top", have_perimeters);
     toggle_field("only_one_perimeter_first_layer", config->opt_int("perimeters") > 1);
     toggle_field("overhangs_width", config->option<ConfigOptionFloatOrPercent>("overhangs_width_speed")->value > 0);