Behavior of the "cog" icon is changed to avoid misunderstandings appear in issue #4891:

"Cog" icon is enabled now every time, but it will had next behavior:
1. Add physical printer, if logical printer is selected
2. Edit physical printer, if it is selected.

 + PresetComboBox: Fixed the black rectangle instead of icon for the "Add/Remove presets" item

src/slic3r/GUI/PresetComboBoxes.cpp

@@ -248,6 +248,51 @@ void PresetComboBox::update(std::string select_preset_name)
     Thaw();
 }
 
+void PresetComboBox::edit_physical_printer()
+{
+    if (!m_preset_bundle->physical_printers.has_selection())
+        return;
+
+    PhysicalPrinterDialog dlg(this->GetString(this->GetSelection()));
+    if (dlg.ShowModal() == wxID_OK)
+        update();
+}
+
+void PresetComboBox::add_physical_printer()
+{
+    if (PhysicalPrinterDialog(wxEmptyString).ShowModal() == wxID_OK)
+        update();
+}
+
+bool PresetComboBox::del_physical_printer(const wxString& note_string/* = wxEmptyString*/)
+{
+    const std::string& printer_name = m_preset_bundle->physical_printers.get_selected_full_printer_name();
+    if (printer_name.empty())
+        return false;
+
+    wxString msg;
+    if (!note_string.IsEmpty())
+        msg += note_string + "\n";
+    msg += format_wxstr(_L("Are you sure you want to delete \"%1%\" printer?"), printer_name);
+
+    if (wxMessageDialog(this, msg, _L("Delete Physical Printer"), wxYES_NO | wxNO_DEFAULT | wxICON_QUESTION).ShowModal() != wxID_YES)
+        return false;
+
+    m_preset_bundle->physical_printers.delete_selected_printer();
+
+    this->update();
+
+    if (dynamic_cast<PlaterPresetComboBox*>(this) != nullptr)
+        wxGetApp().get_tab(m_type)->update_preset_choice();
+    else if (dynamic_cast<TabPresetComboBox*>(this) != nullptr)
+    {
+        wxGetApp().get_tab(m_type)->update_btns_enabling();
+        wxGetApp().plater()->sidebar().update_presets(m_type);
+    }
+
+    return true;
+}
+
 void PresetComboBox::update()
 {
     this->update(into_u8(this->GetString(this->GetSelection())));
@@ -313,7 +358,7 @@ wxBitmap* PresetComboBox::get_bmp(  std::string bitmap_key, bool wide_icons, con
             // Paint a red flag for incompatible presets.
             bmps.emplace_back(is_compatible ? bitmap_cache().mkclear(norm_icon_width, icon_height) : m_bitmapIncompatible.bmp());
 
-        if (m_type == Preset::TYPE_FILAMENT)
+        if (m_type == Preset::TYPE_FILAMENT && !filament_rgb.empty())
         {
             unsigned char rgb[3];
             // Paint the color bars.
@@ -643,27 +688,10 @@ void PlaterPresetComboBox::show_edit_menu()
 
     if (this->is_selected_physical_printer()) {
         append_menu_item(menu, wxID_ANY, _L("Edit physical printer"), "",
-        [this](wxCommandEvent&) {
+            [this](wxCommandEvent&) { this->edit_physical_printer(); }, "cog", menu, []() { return true; }, wxGetApp().plater());
-            PhysicalPrinterDialog dlg(this->GetString(this->GetSelection()));
-            if (dlg.ShowModal() == wxID_OK)
-                update();
-        }, "cog", menu, []() { return true; }, wxGetApp().plater());
 
         append_menu_item(menu, wxID_ANY, _L("Delete physical printer"), "",
-        [this](wxCommandEvent&) {
+            [this](wxCommandEvent&) { this->del_physical_printer(); }, "cross", menu, []() { return true; }, wxGetApp().plater());
-            const std::string& printer_name = m_preset_bundle->physical_printers.get_selected_full_printer_name();
-            if (printer_name.empty())
-                return;
-
-            const wxString msg = from_u8((boost::format(_u8L("Are you sure you want to delete \"%1%\" printer?")) % printer_name).str());
-            if (wxMessageDialog(this, msg, _L("Delete Physical Printer"), wxYES_NO | wxNO_DEFAULT | wxICON_QUESTION).ShowModal() != wxID_YES)
-                return;
-
-            m_preset_bundle->physical_printers.delete_selected_printer();
-
-            wxGetApp().get_tab(m_type)->update_preset_choice();
-            update();
-        }, "cross", menu, []() { return true; }, wxGetApp().plater());
     }
     else
         append_menu_item(menu, wxID_ANY, _L("Add/Remove presets"), "",
@@ -672,11 +700,7 @@ void PlaterPresetComboBox::show_edit_menu()
             }, "edit_uni", menu, []() { return true; }, wxGetApp().plater());
 
     append_menu_item(menu, wxID_ANY, _L("Add physical printer"), "",
-        [this](wxCommandEvent&) {
+        [this](wxCommandEvent&) { this->add_physical_printer(); }, "edit_uni", menu, []() { return true; }, wxGetApp().plater());
-            PhysicalPrinterDialog dlg(wxEmptyString);
-            if (dlg.ShowModal() == wxID_OK)
-                update();
-        }, "edit_uni", menu, []() { return true; }, wxGetApp().plater());
 
     wxGetApp().plater()->PopupMenu(menu);
 }

src/slic3r/GUI/PresetComboBoxes.hpp

@@ -59,6 +59,10 @@ public:
 
     void update(std::string select_preset);
 
+    void edit_physical_printer();
+    void add_physical_printer();
+    bool del_physical_printer(const wxString& note_string = wxEmptyString);
+
     virtual void update();
     virtual void msw_rescale();
 

src/slic3r/GUI/Tab.cpp

@@ -202,9 +202,7 @@ void Tab::create_preset_tab()
     // TRN "Save current Settings"
     m_btn_save_preset->SetToolTip(from_u8((boost::format(_utf8(L("Save current %s"))) % m_title).str()));
     m_btn_delete_preset->SetToolTip(_(L("Delete this preset")));
-    m_btn_delete_preset->Disable();
+    m_btn_delete_preset->Hide();
-    if (m_btn_edit_ph_printer)
-        m_btn_edit_ph_printer->Disable();
 
     add_scaled_button(panel, &m_question_btn, "question");
     m_question_btn->SetToolTip(_(L("Hover the cursor over buttons to find more information \n"
@@ -339,11 +337,12 @@ void Tab::create_preset_tab()
     }));
 
     if (m_btn_edit_ph_printer)
-        m_btn_edit_ph_printer->Bind(wxEVT_BUTTON, ([this](wxCommandEvent e) { 
+        m_btn_edit_ph_printer->Bind(wxEVT_BUTTON, [this](wxCommandEvent e) {
-        PhysicalPrinterDialog dlg(m_presets_choice->GetString(m_presets_choice->GetSelection()));
+            if (m_preset_bundle->physical_printers.has_selection())
-        if (dlg.ShowModal() == wxID_OK)
+                m_presets_choice->edit_physical_printer();
-            update_tab_ui(); 
+            else
-     }));
+                m_presets_choice->add_physical_printer();
+        });
 
     // Fill cache for mode bitmaps
     m_mode_bitmap_cache.reserve(3);
@@ -2927,17 +2926,15 @@ void Tab::rebuild_page_tree()
 
 void Tab::update_btns_enabling()
 {
-    // we can't delete last preset from the physical printer
+    // we can delete any preset from the physical printer
-    if (m_type == Preset::TYPE_PRINTER && m_preset_bundle->physical_printers.has_selection())
+    // and any user preset
-        m_btn_delete_preset->Enable(m_preset_bundle->physical_printers.get_selected_printer().preset_names.size() > 1);
-    else {
     const Preset& preset = m_presets->get_edited_preset();
-        m_btn_delete_preset->Enable(!preset.is_default && !preset.is_system);
+    m_btn_delete_preset->Show(m_type == Preset::TYPE_PRINTER && m_preset_bundle->physical_printers.has_selection() || 
-    }
+                              !preset.is_default && !preset.is_system);
 
-    // we can edit physical printer only if it's selected in the list 
     if (m_btn_edit_ph_printer)
-        m_btn_edit_ph_printer->Enable(m_preset_bundle->physical_printers.has_selection());
+        m_btn_edit_ph_printer->SetToolTip( m_preset_bundle->physical_printers.has_selection() ?
+                                           _L("Edit physical printer") : _L("Add physical printer"));
 }
 
 void Tab::update_preset_choice()
@@ -3336,7 +3333,7 @@ void Tab::save_preset(std::string name /*= ""*/, bool detach)
     // Update the selection boxes at the plater.
     on_presets_changed();
     // If current profile is saved, "delete preset" button have to be enabled
-    m_btn_delete_preset->Enable(true);
+    m_btn_delete_preset->Show();
 
     if (m_type == Preset::TYPE_PRINTER)
         static_cast<TabPrinter*>(this)->m_initial_extruders_count = static_cast<TabPrinter*>(this)->m_extruders_count;
@@ -3389,8 +3386,16 @@ void Tab::delete_preset()
     PhysicalPrinterCollection& physical_printers = m_preset_bundle->physical_printers;
     wxString msg;
     if (m_presets_choice->is_selected_physical_printer())
-        msg = from_u8((boost::format(_u8L("Are you sure you want to delete \"%1%\" preset from the physical printer \"%2%\"?")) 
+    {
-                                     % current_preset.name % physical_printers.get_selected_printer_name()).str());
+        PhysicalPrinter& printer = physical_printers.get_selected_printer();
+        if (printer.preset_names.size() == 1) {
+            if (m_presets_choice->del_physical_printer(_L("It's a last preset for this physical printer.")))
+                Layout();
+            return;
+        }
+        
+        msg = format_wxstr(_L("Are you sure you want to delete \"%1%\" preset from the physical printer \"%2%\"?"), current_preset.name, printer.name);
+    }
     else
     {
         if (m_type == Preset::TYPE_PRINTER && !physical_printers.empty())
@@ -3431,11 +3436,6 @@ void Tab::delete_preset()
     if (m_presets_choice->is_selected_physical_printer()) {
         PhysicalPrinter& printer = physical_printers.get_selected_printer();
 
-        if (printer.preset_names.size() == 1) {
-            wxMessageDialog dialog(nullptr, _L("It's a last for this physical printer. We can't delete it"), _L("Information"), wxICON_INFORMATION | wxOK);
-            dialog.ShowModal();
-            return;
-        }
         // just delete this preset from the current physical printer
         printer.delete_preset(m_presets->get_edited_preset().name);
         // select first from the possible presets for this printer