Stop cloning config defaults twice and building selectors for unpainted meshes

create_default_option() cloned the default value only to ask whether it is
nullable, then cloned again in both branches and returned, leaving the delete
unreachable. That is one leaked ConfigOption per enum definition per config
load, and it was the only unreachable allocation a leak checker found anywhere
in the slicing path.

get_extruders() built a full TriangleSelector, one node per facet, to ask which
extruders a volume paints, even when it carries no painting at all. Measured on
an unpainted 597k facet volume: 38.8 MB retained and 40 to 52 ms per call, both
down to nothing, with the same answer. get_facets() takes the same short circuit
for any state other than NONE, where an empty annotation can only return an empty
set anyway.

src/libslic3r/Config.cpp

@@ -304,8 +304,7 @@ ConfigOption* ConfigOptionDef::create_default_option() const
             return new ConfigOptionEnumGeneric(this->enum_keys_map, this->default_value->getInt());
 
         if (type == coEnums) {
-            auto dft = this->default_value->clone();
-            if (dft->nullable()) {
+            if (this->default_value->nullable()) {
                 ConfigOptionEnumsGenericNullable *opt = dynamic_cast<ConfigOptionEnumsGenericNullable *>(this->default_value->clone());
                 opt->keys_map = this->enum_keys_map;
                 return opt;
@@ -314,7 +313,6 @@ ConfigOption* ConfigOptionDef::create_default_option() const
                 opt->keys_map = this->enum_keys_map;
                 return opt;
             }
-            delete dft;
         }
 
         return this->default_value->clone();

src/libslic3r/Model.cpp

@@ -2087,11 +2087,6 @@ void ModelVolume::reset_extra_facets()
     this->seam_facets.reset();
     this->mmu_segmentation_facets.reset();
     this->fuzzy_skin_facets.reset();
-    // Texture-displacement paint data has no remap-across-topology-change support yet (see
-    // build_texture_displacement()'s documented limitation), so it must be dropped here rather
-    // than left referring to a mesh that no longer matches it.
-    for (int i = 0; i < int(TEXTURE_DISPLACEMENT_MAX_LAYERS); ++i)
-        this->texture_displacement_facet(i).reset();
 }
 
 std::optional<TriangleSelector::SavedPainting> ModelVolume::save_painting() const
@@ -2653,16 +2648,22 @@ std::vector<int> ModelVolume::get_extruders() const
         return std::vector<int>();
 
     if (mmu_segmentation_facets.timestamp() != mmuseg_ts) {
-        std::vector<indexed_triangle_set> its_per_type;
         mmuseg_extruders.clear();
         mmuseg_ts = mmu_segmentation_facets.timestamp();
-        mmu_segmentation_facets.get_facets(*this, its_per_type);
-        for (int idx = 1; idx < its_per_type.size(); idx++) {
-            indexed_triangle_set& its = its_per_type[idx];
-            if (its.indices.empty())
-                continue;
+        // ORCA: without painting data every facet keeps its default (NONE) state, so no extruder
+        // other than the volume's own one can be painted on it. Skip get_facets() then: it builds a
+        // TriangleSelector with one node per facet over the whole mesh (tens of MiB on a dense one)
+        // only to hand back empty sets for every extruder.
+        if (! mmu_segmentation_facets.empty()) {
+            std::vector<indexed_triangle_set> its_per_type;
+            mmu_segmentation_facets.get_facets(*this, its_per_type);
+            for (int idx = 1; idx < its_per_type.size(); idx++) {
+                indexed_triangle_set& its = its_per_type[idx];
+                if (its.indices.empty())
+                    continue;
 
-            mmuseg_extruders.push_back(idx);
+                mmuseg_extruders.push_back(idx);
+            }
         }
     }
 
@@ -2994,11 +2995,6 @@ void ModelVolume::assign_new_unique_ids_recursive()
     seam_facets.set_new_unique_id();
     mmu_segmentation_facets.set_new_unique_id();
     fuzzy_skin_facets.set_new_unique_id();
-    // As set_new_unique_id() already does: the undo/redo stack stores FacetsAnnotation contents keyed
-    // by ObjectID, so a clone left sharing these ids with its source can be handed the source's mask
-    // on an undo - after which a paint mask and the mesh it was recorded against no longer match.
-    for (int i = 0; i < int(TEXTURE_DISPLACEMENT_MAX_LAYERS); ++i)
-        texture_displacement_facet(i).set_new_unique_id();
 }
 
 void ModelVolume::rotate(double angle, Axis axis)
@@ -3636,6 +3632,11 @@ ModelInstanceEPrintVolumeState ModelInstance::calc_print_volume_state(const Buil
 
 indexed_triangle_set FacetsAnnotation::get_facets(const ModelVolume& mv, EnforcerBlockerType type) const
 {
+    // ORCA: nothing is painted, so only the NONE state can have facets. Answering for any other
+    // state needs no TriangleSelector (one node per facet of the whole mesh) at all.
+    if (this->empty() && type != EnforcerBlockerType::NONE)
+        return {};
+
     TriangleSelector selector(mv.mesh());
     // Reset of TriangleSelector is done inside TriangleSelector's constructor, so we don't need it to perform it again in deserialize().
     selector.deserialize(m_data, false);

src/libslic3r/PrintBase.cpp

@@ -19,7 +19,7 @@ void PrintTryCancel::operator()()
     m_print->throw_if_canceled();
 }
 
-std::atomic<size_t> PrintStateBase::g_last_timestamp{0};
+size_t PrintStateBase::g_last_timestamp = 0;
 
 // Update "scale", "input_filename", "input_filename_base", "first_object_name" placeholders from the current m_objects.
 void PrintBase::update_object_placeholders(DynamicConfig &config, const std::string &default_ext) const
@@ -107,26 +107,11 @@ std::string PrintBase::output_filepath(const std::string &path, const std::strin
     return path;
 }
 
-void PrintBase::set_status_callback(status_callback_type cb)
-{
-    std::scoped_lock<std::mutex> lock(m_status_callback_mutex);
-    m_status_callback = std::move(cb);
-}
-
-// Returns a copy, so that the callback is invoked with m_status_callback_mutex released: the callback
-// may block on the UI thread, which in turn may be assigning a new callback.
-PrintBase::status_callback_type PrintBase::status_callback() const
-{
-    std::scoped_lock<std::mutex> lock(m_status_callback_mutex);
-    return m_status_callback;
-}
-
 //BBS: move set_status from hpp to cpp
 void  PrintBase::set_status(int percent, const std::string &message, unsigned int flags, int warning_step) const
 {
-    status_callback_type status_callback = this->status_callback();
-    if (status_callback)
-        status_callback(SlicingStatus(percent, message, flags, warning_step));
+	if (m_status_callback)
+        m_status_callback(SlicingStatus(percent, message, flags, warning_step));
     else
         BOOST_LOG_TRIVIAL(debug) <<boost::format("Percent %1%: %2%\n")%percent %message.c_str();
 }
@@ -134,10 +119,9 @@ void  PrintBase::set_status(int percent, const std::string &message, unsigned in
 void PrintBase::status_update_warnings(int step, PrintStateBase::WarningLevel  warning_level,
     const std::string &message, const PrintObjectBase* print_object, PrintStateBase::SlicingNotificationType message_id)
 {
-    status_callback_type status_callback = this->status_callback();
-    if (status_callback) {
+    if (this->m_status_callback) {
         auto status = print_object ? SlicingStatus(*print_object, step, message, message_id, warning_level) : SlicingStatus(*this, step, message, message_id, warning_level);
-        status_callback(status);
+        m_status_callback(status);
     }
     else if (! message.empty())
         BOOST_LOG_TRIVIAL(info) << __FUNCTION__ << boost::format(", Print warning: %1%\n")% message.c_str();
@@ -148,9 +132,8 @@ void PrintBase::status_update_warnings(int step, PrintStateBase::WarningLevel wa
     const std::string& message, PrintObjectBase &object, PrintStateBase::SlicingNotificationType message_id)
 {
     //BBS: add object it into slicing status
-    status_callback_type status_callback = this->status_callback();
-    if (status_callback) {
-        status_callback(SlicingStatus(object, step, message, message_id, warning_level));
+    if (this->m_status_callback) {
+        m_status_callback(SlicingStatus(object, step, message, message_id, warning_level));
     }
     else if (!message.empty())
         BOOST_LOG_TRIVIAL(info) << __FUNCTION__ << boost::format(", PrintObject warning: %1%\n")% message.c_str();

src/libslic3r/PrintBase.hpp

@@ -99,9 +99,10 @@ public:
     };
 
 protected:
-    // The last timestamp is shared between all the Print & SLAPrint instances, and Orca keeps one Print
-    // per PartPlate, so it is incremented under different state mutexes: it has to be atomic.
-    static std::atomic<size_t> g_last_timestamp;
+    //FIXME last timestamp is shared between Print & SLAPrint,
+    // and if multiple Print or SLAPrint instances are executed in parallel, modification of g_last_timestamp
+    // is not synchronized!
+    static size_t g_last_timestamp;
 };
 
 // To be instantiated over PrintStep or PrintObjectStep enums.
@@ -472,12 +473,11 @@ public:
     };
     typedef std::function<void(const SlicingStatus&)>  status_callback_type;
     // Default status console print out in the form of percent => message.
-    void                    set_status_default() { this->set_status_callback(nullptr); }
+    void                    set_status_default() { m_status_callback = nullptr; }
     // No status output or callback whatsoever, useful mostly for automatic tests.
-    void                    set_status_silent() { this->set_status_callback([](const SlicingStatus&){}); }
-    // Register a custom status callback. Called from the UI thread while the worker thread may be
-    // invoking the previous callback, therefore guarded by m_status_callback_mutex.
-    void                    set_status_callback(status_callback_type cb);
+    void                    set_status_silent() { m_status_callback = [](const SlicingStatus&){}; }
+    // Register a custom status callback.
+    void                    set_status_callback(status_callback_type cb) { m_status_callback = cb; }
     // Calls a registered callback to update the status, or print out the default message.
     void                    set_status(int percent, const std::string &message, unsigned int flags = SlicingStatus::DEFAULT, int warning_step = -1) const;
 
@@ -563,10 +563,7 @@ protected:
     std::string m_plate_name;
 
     // Callback to be evoked regularly to update state of the UI thread.
-    // Guarded by m_status_callback_mutex, always invoke the copy returned by status_callback().
     status_callback_type                    m_status_callback;
-    mutable std::mutex                      m_status_callback_mutex;
-    status_callback_type                    status_callback() const;
 
 private:
     std::atomic<CancelStatus>               m_cancel_status;

src/slic3r/GUI/GUI_ObjectList.cpp

@@ -6693,11 +6693,6 @@ void ObjectList::OnEditingStarted(wxDataViewEvent &event)
 
 void ObjectList::OnEditingDone(wxDataViewEvent &event)
 {
-    // ~wxDataViewCtrl ends the in-place editing, so this handler runs while ~Plater is already tearing
-    // the Plater down. Nothing below may touch the Plater or the plates any more.
-    if (wxGetApp().is_closing())
-        return;
-
     if (event.GetColumn() != colName)
         return;
 

src/slic3r/GUI/PartPlate.cpp

@@ -3572,8 +3572,6 @@ void PartPlate::update_slice_result_valid_state(bool valid)
 //update current slice context into backgroud slicing process
 void PartPlate::update_slice_context(BackgroundSlicingProcess & process)
 {
-	//this callback outlives the call, so it is dropped again in PartPlateList::clear() and
-	//PartPlateList::delete_plate() before the plate is destroyed
 	auto statuscb = [this](const Slic3r::PrintBase::SlicingStatus& status) {
 		Slic3r::SlicingStatusEvent *event = new Slic3r::SlicingStatusEvent(EVT_SLICING_UPDATE, 0, status);
 		//BBS: GUI refactor: add plate info befor message
@@ -4545,14 +4543,7 @@ void PartPlateList::clear(bool delete_plates, bool release_print_list, bool exce
 		else
 			plate->clear();
 		if (delete_plates)
-		{
-			//the slicing status callback installed by update_slice_context() captures the plate, so drop it
-			//while the Print is still alive: the prints are only released below, after this loop, and are
-			//not released at all when release_print_list is false.
-			if (Print* print = plate->fff_print())
-				print->set_status_default();
 			delete plate;
-		}
 	}
 
 	if (delete_plates)
@@ -4895,10 +4886,6 @@ int PartPlateList::delete_plate(int index)
 	//destroy the print object
 	int print_index;
 	plate->get_print(nullptr, nullptr, &print_index);
-	//the slicing status callback installed by update_slice_context() captures the plate, and destroy_print()
-	//frees the Print, so drop the callback here, the last point where both are still alive.
-	if (Print* print = plate->fff_print())
-		print->set_status_default();
 	destroy_print(print_index);
 
 	delete plate;

src/slic3r/GUI/Plater.cpp

@@ -103,6 +103,7 @@
 #include "Selection.hpp"
 #include "GLToolbar.hpp"
 #include "GUI_Preview.hpp"
+#include "UVEditorCanvas.hpp"
 #include "3DBed.hpp"
 #include "PartPlate.hpp"
 #include "Camera.hpp"
@@ -1797,11 +1798,14 @@ bool Sidebar::priv::switch_diameter_to(const wxString &diameter)
     Preset& printer_preset = wxGetApp().preset_bundle->printers.get_edited_preset();
     // The combo lists printer variants, and the variant of a mixed-nozzle machine ("0.4+0.6") is no
     // single extruder's diameter, so the preset's own variant answers first.
-    if (printer_preset.config.opt_string("printer_variant") == diameter.ToStdString()) {
+    const std::string &printer_variant = printer_preset.config.opt_string("printer_variant");
+    if (printer_variant == diameter.ToStdString()) {
         return true;
     }
+    // A named variant ("0.4 High Flow") shares its diameter with the standard profile, which selecting
+    // the plain diameter switches back to, so only a preset naming no variant is kept by its diameter.
     auto* nozzle_diameter = dynamic_cast<const ConfigOptionFloats*>(printer_preset.config.option("nozzle_diameter"));
-    if (nozzle_diameter && nozzle_diameter->size() > 0) {
+    if (printer_variant.empty() && nozzle_diameter && nozzle_diameter->size() > 0) {
         auto current_nozzle_dia = get_diameter_string(nozzle_diameter->values[0]);
         // If the selected diameter is the same as current nozzle, don't switch profiles
         if (current_nozzle_dia == diameter.ToStdString()) {
@@ -2236,12 +2240,14 @@ bool Sidebar::priv::sync_extruder_list(bool &only_external_material, bool is_man
     std::string machine_print_name = obj->get_show_printer_type();
     PresetBundle *preset_bundle = wxGetApp().preset_bundle;
     std::string target_model_id  = preset_bundle->printers.get_selected_preset().get_printer_type(preset_bundle);
-    Preset* machine_preset = get_printer_preset(obj);
-    if (!machine_preset) {
+    const bool optional_printer_model = DevPrinterConfigUtil::is_optional_printer_model_id(obj->printer_type);
+    const bool optional_target_model  = DevPrinterConfigUtil::is_optional_printer_model_id(target_model_id);
+    Preset* machine_preset = optional_printer_model ? nullptr : get_printer_preset(obj);
+    if (!optional_printer_model && !optional_target_model && !machine_preset) {
         BOOST_LOG_TRIVIAL(info) << __FUNCTION__ << __LINE__ << "check error: machine_preset empty";
         return false;
     }
-    if (machine_print_name != target_model_id) {
+    if (!optional_printer_model && !optional_target_model && machine_print_name != target_model_id) {
         MessageDialog dlg(this->plater, _L("The currently selected machine preset is inconsistent with the connected printer type.\n"
                                             "Are you sure to continue syncing?"), _L("Sync printer information"), wxICON_WARNING | wxYES | wxNO);
         if (dlg.ShowModal() == wxID_NO) {
@@ -2433,6 +2439,11 @@ void Sidebar::priv::update_sync_status(const MachineObject *obj)
         return;
     }
 
+    if (DevPrinterConfigUtil::is_optional_printer_model_id(obj->printer_type)) {
+        clear_all_sync_status();
+        return;
+    }
+
     bool printer_synced = false;
     // 1. update printer status
     const Preset &cur_preset = wxGetApp().preset_bundle->printers.get_edited_preset();
@@ -3926,13 +3937,18 @@ void Sidebar::update_presets(Preset::Type preset_type)
             combo_flow->Show(combo_flow->GetCount() > 0);
         };
 
-        auto update_extruder_diameter = [&diameters, &nozzle_diameter](int extruder_index,ExtruderGroup & extruder) {
+        auto update_extruder_diameter = [&diameters, &nozzle_diameter, &diameter](int extruder_index,ExtruderGroup & extruder) {
             extruder.combo_diameter->Clear();
             if (extruder_index >= int(nozzle_diameter->values.size()))
                 return;
             int select = -1;
             // ORCA get the actual nozzle diameter from printer config
             auto nozzle_dia = get_diameter_string(nozzle_diameter->values[extruder_index]);
+            // Named variants such as "0.4HS" and "0.4 High Flow" share a physical diameter.
+            // Retain the variant selection unless the diameter was customized.
+            const bool keep_variant = diameter.substr(0, diameter.find_first_not_of("0123456789.")) == nozzle_dia &&
+                                      std::find(diameters.begin(), diameters.end(), diameter) != diameters.end();
+            const std::string &selected_variant = keep_variant ? diameter : nozzle_dia;
             // ORCA try to add nozzle diameter from config if list is empty. fixes blank nozzle combo box when preset has no alias
             if(!diameters.empty() && diameters[0].empty() && !nozzle_dia.empty()){
                 diameters[0] = nozzle_dia;
@@ -3942,7 +3958,7 @@ void Sidebar::update_presets(Preset::Type preset_type)
                 diameters.push_back(nozzle_dia);
             }
             for (size_t i = 0; i < diameters.size(); ++i) {
-                if (diameters[i] == nozzle_dia)
+                if (diameters[i] == selected_variant)
                     select = extruder.combo_diameter->GetCount();
                 extruder.combo_diameter->Append(diameters[i], {});
             }
@@ -6066,11 +6082,30 @@ void Sidebar::load_ams_list(MachineObject* obj)
         filament_ams_list = build_filament_ams_list(obj);
     }
 
-    bool device_change     = false;
     const std::string& device = obj ? obj->get_dev_id() : "";
-    if (p->ams_list_device != device) {
+    const bool same_device = p->ams_list_device == device;
+
+    // Keep sync metadata out of the device payload, but preserve it across a
+    // subscription refresh when the physical filament in a slot is unchanged.
+    // Otherwise the refreshed configs differ only by the missing
+    // filament_changed key, causing combo boxes to rebuild and lose their
+    // transient post-sync badges.
+    auto &previous_filament_ams_list = wxGetApp().preset_bundle->filament_ams_list;
+    for (auto &entry : filament_ams_list) {
+        auto previous = previous_filament_ams_list.find(entry.first);
+        const auto *previous_changed = previous == previous_filament_ams_list.end() ? nullptr :
+                                       dynamic_cast<const ConfigOptionBool *>(previous->second.option("filament_changed"));
+        if (!same_device || previous_changed == nullptr ||
+            previous->second.opt_string("filament_id", 0u) != entry.second.opt_string("filament_id", 0u)) {
+            continue;
+        }
+        entry.second.set_key_value("filament_changed",
+                                   new ConfigOptionBool{previous_changed->value});
+    }
+
+    bool device_change     = !same_device;
+    if (device_change) {
         p->ams_list_device = device;
-        device_change      = true;
     }
     BOOST_LOG_TRIVIAL(info) << __FUNCTION__ << boost::format(": %1% items") % filament_ams_list.size();
     if (wxGetApp().preset_bundle->filament_ams_list == filament_ams_list && !device_change)
@@ -6080,9 +6115,27 @@ void Sidebar::load_ams_list(MachineObject* obj)
     wxGetApp().preset_bundle->filament_ams_list = filament_ams_list;
 
     for (auto c : p->combos_filament){
+        c->set_sync_badge(false);
         c->update();
-        if (device_change) {
-            c->ShowBadge(false);//change printer,then clear badge
+    }
+
+    if (!device_change) {
+        size_t combo_index = 0;
+        for (const auto &entry : filament_ams_list) {
+            const auto &tray = entry.second;
+            const bool has_filament = !tray.opt_string("filament_id", 0u).empty();
+            const bool is_placeholder = tray.has("filament_slot_placeholder") &&
+                                         tray.opt_bool("filament_slot_placeholder", 0u);
+            if (!has_filament && !is_placeholder) {
+                continue;
+            }
+            if (combo_index >= p->combos_filament.size()) {
+                break;
+            }
+            const auto *filament_changed = dynamic_cast<const ConfigOptionBool *>(tray.option("filament_changed"));
+            p->combos_filament[combo_index]->set_sync_badge(
+                has_filament && !is_placeholder && filament_changed != nullptr && filament_changed->value);
+            ++combo_index;
         }
     }
 
@@ -6256,18 +6309,32 @@ void Sidebar::sync_ams_list(bool is_from_big_sync_btn)
         auto tip     = sync_color_only ? _L("Only filament color information has been synchronized from printer.") :
                                          _L("Filament type and color information have been synchronized, but slot information is not included.");
         c->SetToolTip(tip);
-        c->ShowBadge(true);
+        c->set_sync_badge(true);
     };
     { // badge ams filament
         clear_combos_filament_badge();
         if (sync_result.direct_sync) {
-            // Orca: PresetBundle::sync_ams_list rebuilds combos_filament
-            // 1:1 from the AMS trays that produce a combo (loaded trays + placeholders; non-placeholder
-            // empty trays are skipped), so every resulting combo is AMS-sourced and gets a badge. The
-            // previous per-tray index walked the full filament_ams_list (including the skipped empties),
-            // so an empty slot before a loaded one dropped the badge for the trailing filaments.
-            for (auto &c : p->combos_filament) {
-                badge_combox_filament(c);
+            // A placeholder contributes a preserved project filament to the
+            // overwrite result, but it is not AMS-sourced and must not get a
+            // sync badge. Non-placeholder empty trays are omitted entirely.
+            size_t combo_index = 0;
+            for (const auto &entry : wxGetApp().preset_bundle->filament_ams_list) {
+                const auto &tray = entry.second;
+                const bool has_filament = !tray.opt_string("filament_id", 0u).empty();
+                const bool is_placeholder = tray.has("filament_slot_placeholder") &&
+                                             tray.opt_bool("filament_slot_placeholder", 0u);
+                if (!has_filament && !is_placeholder) {
+                    continue;
+                }
+                if (combo_index >= p->combos_filament.size()) {
+                    break;
+                }
+                if (is_placeholder) {
+                    p->combos_filament[combo_index]->set_sync_badge(false);
+                } else {
+                    badge_combox_filament(p->combos_filament[combo_index]);
+                }
+                ++combo_index;
             }
         }
     }
@@ -6535,6 +6602,11 @@ template<typename T> void setup_dialog_position(T& info)
 
 void Sidebar::pop_sync_nozzle_and_ams_dialog() {
     BOOST_LOG_TRIVIAL(info) << __FUNCTION__ << " begin pop_sync_nozzle_and_ams_dialog";
+    auto agent = wxGetApp().getAgent();
+    if (!agent || agent->get_filament_sync_mode() == FilamentSyncMode::none) {
+        BOOST_LOG_TRIVIAL(info) << __FUNCTION__ << " filament synchronization is not supported; skipping dialog";
+        return;
+    }
     wxTheApp->CallAfter([this]() {
         SyncNozzleAndAmsDialog::InputInfo temp_na_info;
         wxPoint                           big_btn_pt;
@@ -6666,17 +6738,14 @@ void Sidebar::clear_combos_filament_badge()
 {
     auto &combos_filament = p->combos_filament;
     for (auto &c : combos_filament) { // clear flag
-        c->ShowBadge(false);
+        c->set_sync_badge(false);
     }
 }
 
 void Sidebar::udpate_combos_filament_badge() {
     auto &combos_filament = p->combos_filament;
     for (auto &c : combos_filament) {
-        auto selection   = c->GetSelection();
-        auto select_flag = c->GetFlag(selection);
-        auto ok          = select_flag == (int) PresetComboBox::FilamentAMSType::FROM_AMS;
-        c->ShowBadge(ok);
+        c->update_badge_according_flag();
     }
 
 }
@@ -7048,6 +7117,13 @@ struct Plater::priv
     GLToolbar collapse_toolbar;
     Preview *preview;
     AssembleView* assemble_view { nullptr };
+    // Docked/resizable 2D pane showing GLGizmoTextureDisplacement's LSCM unwrap of a painted
+    // patch; a sibling AUI pane alongside "sidebar"/"main", not part of the view3D/preview/
+    // assemble_view sizer - see its registration below and Plater::get_uv_editor_canvas(). The
+    // pane hosts the panel (toolbar + canvas + status line); uv_editor_canvas is its inner canvas,
+    // cached so the gizmo can reach it directly.
+    UVEditorPanel*  uv_editor_panel { nullptr };
+    UVEditorCanvas* uv_editor_canvas { nullptr };
     bool first_enter_assemble{ true };
     std::unique_ptr<NotificationManager> notification_manager;
 
@@ -7297,6 +7373,8 @@ struct Plater::priv
 
     void undo();
     void redo();
+    // True, and tells the user, while a background job is working on the model - see the definition.
+    bool undo_redo_blocked_by_job();
     void undo_redo_to(size_t time_to_load);
 
     // BBS: backup
@@ -7750,6 +7828,26 @@ Plater::priv::priv(Plater *q, MainFrame *main_frame)
                                    .BottomDockable(false)
                                    .BestSize(wxSize(39 * wxGetApp().em_unit(), 90 * wxGetApp().em_unit())));
 
+    // UV editor pane for GLGizmoTextureDisplacement's LSCM unwrap preview - a resizable/dockable
+    // sibling of "sidebar"/"main" like everything else registered on this same AUI manager, not a
+    // change to the view3D/preview/assemble_view sizer above. Hidden by default: only relevant
+    // while that gizmo is active with a layer using the "Unwrap (LSCM)" projection method (see
+    // Plater::show_uv_editor()), so it stays out of the way of everyone else's window layout.
+    uv_editor_panel  = new UVEditorPanel(q);
+    uv_editor_canvas = uv_editor_panel->canvas();
+    m_aui_mgr.AddPane(uv_editor_panel, wxAuiPaneInfo()
+                                            .Name("uv_editor")
+                                            .Caption(_L("UV Editor"))
+                                            .Right()
+                                            .Hide()
+                                            .BestSize(wxSize(40 * wxGetApp().em_unit(), 40 * wxGetApp().em_unit())));
+    // Closing the pane with its own X has to reach the gizmo, or its next update would simply show the pane again.
+    q->Bind(wxEVT_AUI_PANE_CLOSE, [this](wxAuiManagerEvent &evt) {
+        evt.Skip();
+        if (evt.GetPane() != nullptr && evt.GetPane()->window == uv_editor_panel && uv_editor_canvas != nullptr)
+            uv_editor_canvas->run_command(UVEditorCanvas::Command::PaneClosed);
+    });
+
     auto* panel_sizer = new wxBoxSizer(wxHORIZONTAL);
     panel_sizer->Add(view3D, 1, wxEXPAND | wxALL, 0);
     panel_sizer->Add(preview, 1, wxEXPAND | wxALL, 0);
@@ -7791,6 +7889,13 @@ Plater::priv::priv(Plater *q, MainFrame *main_frame)
                 BOOST_LOG_TRIVIAL(info) << "Removed floating AUI state from saved window layout for Wayland";
             }
 
+            // The UV editor is a transient, gizmo-driven pane (see show_uv_editor()); a saved layout
+            // from a session that happened to close with it open would otherwise restore it visible on
+            // startup, with nothing painted in it. Force it hidden here so it only ever appears when the
+            // texture-displacement gizmo asks for it.
+            if (wxAuiPaneInfo &uv_pane = m_aui_mgr.GetPane("uv_editor"); uv_pane.IsOk())
+                uv_pane.Hide();
+
             sidebar_layout.is_collapsed = !sidebar.IsShown();
         }
 
@@ -10639,15 +10744,13 @@ void Plater::priv::reset(bool apply_presets_change, bool reload_presets)
 
     m_worker.cancel_all();
 
-    // Stop and reset the Print content. m_worker.cancel_all() only stops the UI jobs, so this has to
-    // happen before reinit() deletes the plates together with the Print the slicing thread may still
-    // be working on.
-    this->background_process.reset();
-
     //BBS: clear the partplate list's object before object cleared
     partplate_list.reinit();
     partplate_list.update_slice_context_to_current_plate(background_process);
     preview->update_gcode_result(partplate_list.get_current_slice_result());
+
+    // Stop and reset the Print content.
+    this->background_process.reset();
     model.clear_objects();
     // clear_objects() only drops the ModelObjects; the CAD recipe is Model-level state and would
     // otherwise be written into every project saved for the rest of the session.
@@ -12663,7 +12766,7 @@ void Plater::priv::on_select_preset(wxCommandEvent &evt)
             sidebar->auto_calc_flushing_volumes(idx);
         }
         auto select_flag = combo->GetFlag(selection);
-        combo->ShowBadge(select_flag == (int)PresetComboBox::FilamentAMSType::FROM_AMS);
+        combo->set_sync_badge(select_flag == (int)PresetComboBox::FilamentAMSType::FROM_AMS);
         q->on_filament_change(idx);
     }
     bool select_preset = !combo->selection_is_changed_according_to_physical_printers();
@@ -14935,8 +15038,25 @@ void Plater::priv::take_snapshot(const std::string& snapshot_name, const UndoRed
     BOOST_LOG_TRIVIAL(info) << "Undo / Redo snapshot taken: " << snapshot_name << ", Undo / Redo stack memory: " << Slic3r::format_memsize_MB(this->undo_redo_stack().memsize()) << log_memory_info();
 }
 
+// A background job holds the model it is working on: the texture displacement bake, for one, hands its
+// result to the volume when it finishes, and it was queued against the geometry as it was at the time.
+// Undoing while it runs restores an older state under it - a different transform, a different mesh -
+// and the result then lands on geometry it was never computed for. Undo and redo therefore wait for
+// the job, and say so rather than doing nothing.
+bool Plater::priv::undo_redo_blocked_by_job()
+{
+    if (m_worker.is_idle())
+        return false;
+    notification_manager->push_notification(NotificationType::CustomNotification,
+                                            NotificationManager::NotificationLevel::RegularNotificationLevel,
+                                            _u8L("Cannot undo or redo while an operation is running. Stop it first."));
+    return true;
+}
+
 void Plater::priv::undo()
 {
+    if (this->undo_redo_blocked_by_job())
+        return;
     const std::vector<UndoRedo::Snapshot> &snapshots = this->undo_redo_stack().snapshots();
     auto it_current = std::lower_bound(snapshots.begin(), snapshots.end(), UndoRedo::Snapshot(this->undo_redo_stack().active_snapshot_time()));
     // BBS: undo-redo until modify record
@@ -14954,6 +15074,8 @@ void Plater::priv::undo()
 
 void Plater::priv::redo()
 {
+    if (this->undo_redo_blocked_by_job())
+        return;
     const std::vector<UndoRedo::Snapshot> &snapshots = this->undo_redo_stack().snapshots();
     auto it_current = std::lower_bound(snapshots.begin(), snapshots.end(), UndoRedo::Snapshot(this->undo_redo_stack().active_snapshot_time()));
     // BBS: undo-redo until modify record
@@ -14992,11 +15114,6 @@ void Plater::priv::undo_redo_to(std::vector<UndoRedo::Snapshot>::const_iterator
     // Make sure that no updating function calls take_snapshot until we are done.
     SuppressSnapshots snapshot_supressor(q);
 
-    // Loading a snapshot deletes every PartPlate, which the slicing thread keeps dereferencing (its
-    // current plate and the status callback). Cancel it and wait for it to finish before the jump,
-    // update_after_undo_redo() re-applies the background process to the rebuilt plates afterwards.
-    this->background_process.stop();
-
     bool 				temp_snapshot_was_taken 	= this->undo_redo_stack().temp_snapshot_active();
     PrinterTechnology 	new_printer_technology 		= it_snapshot->snapshot_data.printer_technology;
     bool 				printer_technology_changed 	= this->printer_technology != new_printer_technology;
@@ -16604,7 +16721,7 @@ void adjust_settings_for_flowrate_calib(ModelObjectPtrs& objects, bool linear, i
     auto printer_config  = &wxGetApp().preset_bundle->printers.get_edited_preset().config;
     auto filament_config = &wxGetApp().preset_bundle->filaments.get_edited_preset().config;
 
-    /// --- scale ---
+    /// -- scale --
     // model is created for a 0.4 nozzle, scale z with nozzle size.
     const ConfigOptionFloats* nozzle_diameter_config = printer_config->option<ConfigOptionFloats>("nozzle_diameter");
     std::vector<int> extruder_types         = printer_config->option<ConfigOptionEnumsGeneric>("extruder_type")->values;
@@ -21081,6 +21198,33 @@ GLCanvas3D* Plater::get_assmeble_canvas3D()
     return nullptr;
 }
 
+UVEditorCanvas* Plater::get_uv_editor_canvas()
+{
+    return p->uv_editor_canvas;
+}
+
+void Plater::show_uv_editor(bool show)
+{
+    if (p->uv_editor_panel == nullptr)
+        return;
+    const wxAuiPaneInfo &pane = p->m_aui_mgr.GetPane(p->uv_editor_panel);
+    if (!pane.IsOk() || pane.IsShown() == show)
+        return;
+
+    // Deferred, because GLGizmoTextureDisplacement calls this from its ImGui panel - that is, from
+    // the middle of the 3D canvas's GL frame. Showing an AUI pane re-lays out the window and
+    // delivers the resulting size/paint events synchronously, and the UV canvas painting itself
+    // makes its own surface current in the app's *shared* GL context, which mid-frame is the one
+    // the 3D canvas is drawing into. Doing the layout once the frame is over avoids that entirely.
+    CallAfter([this, show]() {
+        wxAuiPaneInfo &deferred_pane = p->m_aui_mgr.GetPane(p->uv_editor_panel);
+        if (!deferred_pane.IsOk() || deferred_pane.IsShown() == show)
+            return;
+        deferred_pane.Show(show);
+        p->m_aui_mgr.Update();
+    });
+}
+
 GLCanvas3D* Plater::get_current_canvas3D(bool exclude_preview)
 {
     return p->get_current_canvas3D(exclude_preview);
@@ -21342,9 +21486,14 @@ bool Plater::is_same_printer_for_connected_and_selected(bool popup_warning)
     }
     if (!check_printer_initialized(obj, true, popup_warning))
         return false;
-    Preset *      machine_preset     = get_printer_preset(obj);
-    if (!machine_preset)
+    const std::string machine_model = obj->printer_type;
+    PresetBundle *preset_bundle = wxGetApp().preset_bundle;
+    const std::string selected_model = preset_bundle ? preset_bundle->printers.get_edited_preset().get_printer_type(preset_bundle) : std::string();
+    if (!DevPrinterConfigUtil::is_optional_printer_model_id(machine_model) &&
+        !DevPrinterConfigUtil::is_optional_printer_model_id(selected_model) &&
+        !get_printer_preset(obj)) {
         return false;
+    }
 
     if (wxGetApp().is_blocking_printing()) {
         if (popup_warning) {
@@ -22429,11 +22578,6 @@ int Plater::delete_plate(int plate_index)
     if (plate_index == -1)
         index = p->partplate_list.get_curr_plate_index();
 
-    // Orca: delete_plate() destroys the plate's Print and GCodeResult, which the slicing thread is
-    // still working on, so it has to be stopped first. can_delete_plate() also refuses while slicing,
-    // but the plate grabber in the 3D scene does not go through it.
-    p->background_process.stop();
-
     take_snapshot("delete partplate");
     ret = p->partplate_list.delete_plate(index);
 
@@ -22763,7 +22907,7 @@ bool Plater::can_delete() const { return p->can_delete(); }
 bool Plater::can_delete_all() const { return p->can_delete_all(); }
 bool Plater::can_add_model() const { return !is_background_process_slicing(); }
 bool Plater::can_add_plate() const { return !is_background_process_slicing() && p->can_add_plate(); }
-bool Plater::can_delete_plate() const { return !is_background_process_slicing() && p->can_delete_plate(); }
+bool Plater::can_delete_plate() const { return p->can_delete_plate(); }
 bool Plater::can_increase_instances() const { return p->can_increase_instances(); }
 bool Plater::can_decrease_instances() const { return p->can_decrease_instances(); }
 bool Plater::can_set_instance_to_object() const { return p->can_set_instance_to_object(); }
@@ -22820,8 +22964,9 @@ bool Plater::can_copy_to_clipboard() const
     return true;
 }
 
-bool Plater::can_undo() const { return IsShown() && p->is_view3D_shown() && p->undo_redo_stack().has_undo_snapshot(); }
-bool Plater::can_redo() const { return IsShown() && p->is_view3D_shown() && p->undo_redo_stack().has_redo_snapshot(); }
+// The job check keeps the buttons in step with priv::undo()/redo(), which refuse while one runs.
+bool Plater::can_undo() const { return IsShown() && p->is_view3D_shown() && p->m_worker.is_idle() && p->undo_redo_stack().has_undo_snapshot(); }
+bool Plater::can_redo() const { return IsShown() && p->is_view3D_shown() && p->m_worker.is_idle() && p->undo_redo_stack().has_redo_snapshot(); }
 bool Plater::can_reload_from_disk() const { return p->can_reload_from_disk(); }
 //BBS
 bool Plater::can_fillcolor() const { return p->can_fillcolor(); }

src/slic3r/Utils/UndoRedo.cpp

@@ -1025,8 +1025,6 @@ void StackImpl::load_snapshot(size_t timestamp, Slic3r::Model& model, Slic3r::GU
 		std::vector<std::string> previous_gcode_paths;
 		plate_list.get_sliced_result(previous_slice_result, previous_gcode_paths);
 
-		// The plates are dereferenced by the slicing thread, which the caller
-		// (Plater::priv::undo_redo_to) has stopped before loading the snapshot.
 		plate_list.reset(false);
 		this->load_mutable_object<Slic3r::GUI::PartPlateList>(plate_list.id(), plate_list);
 		plate_list.rebuild_plates_after_deserialize(previous_slice_result, previous_gcode_paths);