diff --git a/resources/icons/action_undo.png b/resources/icons/action_undo.png
new file mode 100644
index 000000000..866ae9773
Binary files /dev/null and b/resources/icons/action_undo.png differ
diff --git a/resources/icons/arrow_undo.png b/resources/icons/arrow_undo.png
new file mode 100644
index 000000000..6972c5e59
Binary files /dev/null and b/resources/icons/arrow_undo.png differ
diff --git a/resources/localization/uk/Slic3rPE_.mo b/resources/localization/uk/Slic3rPE_.mo
new file mode 100644
index 000000000..c980ae64d
Binary files /dev/null and b/resources/localization/uk/Slic3rPE_.mo differ
diff --git a/slic3r.pl b/slic3r.pl
index a3cc3cfc2..d9bed0ab6 100755
--- a/slic3r.pl
+++ b/slic3r.pl
@@ -12,7 +12,7 @@ BEGIN {
 use File::Basename qw(basename);
 use Getopt::Long qw(:config no_auto_abbrev);
 use List::Util qw(first);
-use POSIX qw(setlocale LC_NUMERIC);
+#use POSIX qw(setlocale LC_NUMERIC);
 use Slic3r;
 use Slic3r::Geometry qw(deg2rad);
 use Time::HiRes qw(gettimeofday tv_interval);
@@ -112,7 +112,7 @@ if ((!@ARGV || $opt{gui}) && !$opt{no_gui} && !$opt{save} && eval "require Slic3
         $Slic3r::GUI::autosave      = $opt{autosave};
     }
     $gui = Slic3r::GUI->new;
-    setlocale(LC_NUMERIC, 'C');
+    #setlocale(LC_NUMERIC, 'C');
     $gui->{mainframe}->load_config_file($_) for @{$opt{load}};
     $gui->{mainframe}->load_config($cli_config);
     my @input_files = @ARGV;
diff --git a/xs/src/slic3r/GUI/Field.hpp b/xs/src/slic3r/GUI/Field.hpp
index 0d8c237d2..56de333cf 100644
--- a/xs/src/slic3r/GUI/Field.hpp
+++ b/xs/src/slic3r/GUI/Field.hpp
@@ -18,6 +18,7 @@
 
 //#include "slic3r_gui.hpp"
 #include "GUI.hpp"
+#include "Utils.hpp"
 
 namespace Slic3r { namespace GUI {
 
@@ -31,7 +32,15 @@ wxString double_to_string(double const value);
 class Field {
 protected:
     // factory function to defer and enforce creation of derived type. 
-    virtual void	PostInitialize() { BUILD(); }
+    virtual void	PostInitialize(){
+		m_Undo_btn = new wxButton(m_parent, wxID_ANY, "", wxDefaultPosition, wxDefaultSize, wxBU_EXACTFIT|wxNO_BORDER);
+		// use bouth of temporary_icons till don't have "undo_icon" 
+		m_Undo_btn->SetBitmap(wxBitmap(from_u8(__WXMSW__ ? var("action_undo.png") : var("arrow_undo.png")), wxBITMAP_TYPE_PNG));
+		auto color = wxSystemSettings::GetColour(wxSYS_COLOUR_WINDOW);
+		m_Undo_btn->SetBackgroundColour(color);
+		m_Undo_btn->Hide();
+    	BUILD();
+    }
     
     /// Finish constructing the Field's wxWidget-related properties, including setting its own sizer, etc.
     virtual void	BUILD() = 0;
@@ -73,6 +82,7 @@ public:
     virtual void		disable() = 0;
 
 	wxStaticText*		m_Label = nullptr;
+	wxButton*			m_Undo_btn = nullptr;
 
     /// Fires the enable or disable function, based on the input.
     inline void			toggle(bool en) { en ? enable() : disable(); }
diff --git a/xs/src/slic3r/GUI/GUI.cpp b/xs/src/slic3r/GUI/GUI.cpp
index f9561d7b6..1ccf80365 100644
--- a/xs/src/slic3r/GUI/GUI.cpp
+++ b/xs/src/slic3r/GUI/GUI.cpp
@@ -240,6 +240,7 @@ bool select_language(wxArrayString & names,
 		g_wxLocale->Init(identifiers[index]);
 		g_wxLocale->AddCatalogLookupPathPrefix(wxPathOnly(localization_dir()));
 		g_wxLocale->AddCatalog(g_wxApp->GetAppName());
+		wxSetlocale(LC_NUMERIC, "C");
 		return true;
 	}
 	return false;
@@ -268,6 +269,7 @@ bool load_language()
 			g_wxLocale->Init(identifiers[i]);
 			g_wxLocale->AddCatalogLookupPathPrefix(wxPathOnly(localization_dir()));
 			g_wxLocale->AddCatalog(g_wxApp->GetAppName());
+			wxSetlocale(LC_NUMERIC, "C");
 			return true;
 		}
 	}
@@ -507,7 +509,7 @@ wxApp* get_app(){
 
 wxColour* get_modified_label_clr()
 {
-	return new wxColour(254, 189, 101);
+	return new wxColour(253, 88, 0);
 }
 
 void create_combochecklist(wxComboCtrl* comboCtrl, std::string text, std::string items, bool initial_value)
@@ -567,13 +569,13 @@ AppConfig* get_app_config()
 	return g_AppConfig;
 }
 
-wxString L_str(std::string str)
+wxString L_str(const std::string &str)
 {
 	//! Explicitly specify that the source string is already in UTF-8 encoding
 	return wxGetTranslation(wxString(str.c_str(), wxConvUTF8));
 }
 
-wxString from_u8(std::string str)
+wxString from_u8(const std::string &str)
 {
 	return wxString::FromUTF8(str.c_str());
 }
diff --git a/xs/src/slic3r/GUI/GUI.hpp b/xs/src/slic3r/GUI/GUI.hpp
index 7a8039e64..b7e67af92 100644
--- a/xs/src/slic3r/GUI/GUI.hpp
+++ b/xs/src/slic3r/GUI/GUI.hpp
@@ -119,9 +119,9 @@ void create_combochecklist(wxComboCtrl* comboCtrl, std::string text, std::string
 int combochecklist_get_flags(wxComboCtrl* comboCtrl);
 
 // Return translated std::string as a wxString
-wxString	L_str(std::string str);
+wxString	L_str(const std::string &str);
 // Return wxString from std::string in UTF8
-wxString	from_u8(std::string str);
+wxString	from_u8(const std::string &str);
 
 }
 }
diff --git a/xs/src/slic3r/GUI/OptionsGroup.cpp b/xs/src/slic3r/GUI/OptionsGroup.cpp
index 14142d207..138496b2e 100644
--- a/xs/src/slic3r/GUI/OptionsGroup.cpp
+++ b/xs/src/slic3r/GUI/OptionsGroup.cpp
@@ -3,6 +3,7 @@
 
 #include <utility>
 #include <wx/numformatter.h>
+#include "Utils.hpp"
 
 namespace Slic3r { namespace GUI {
 
@@ -104,6 +105,7 @@ void OptionsGroup::append_line(const Line& line) {
 		const auto& option = option_set.front();
 		const auto& field = build_field(option);
 
+		sizer->Add(field->m_Undo_btn);
 		if (is_window_field(field))
 			sizer->Add(field->getWindow(), 0, wxEXPAND | wxALL, wxOSX ? 0 : 5);
 		if (is_sizer_field(field))
@@ -116,9 +118,8 @@ void OptionsGroup::append_line(const Line& line) {
     // Build a label if we have it
 	wxStaticText* label=nullptr;
     if (label_width != 0) {
-		/*auto*/ label = new wxStaticText(parent(), wxID_ANY, line.label + (line.label.IsEmpty() ? "" : ":"), 
+		label = new wxStaticText(parent(), wxID_ANY, line.label + (line.label.IsEmpty() ? "" : ":"), 
 							wxDefaultPosition, wxSize(label_width, -1));
-// 		label->SetBackgroundColour(*new wxColour(254, 189, 101));
         label->SetFont(label_font);
         label->Wrap(label_width); // avoid a Linux/GTK bug
 		grid_sizer->Add(label, 0, wxALIGN_CENTER_VERTICAL,0);
@@ -134,25 +135,24 @@ void OptionsGroup::append_line(const Line& line) {
 	}
 	
 	// if we have a single option with no sidetext just add it directly to the grid sizer
-    if (option_set.size() == 1 && option_set.front().opt.sidetext.size() == 0 &&
-        option_set.front().side_widget == nullptr && line.get_extra_widgets().size() == 0) {
-        const auto& option = option_set.front();
-        const auto& field = build_field(option, label);
-//!         std::cerr << "single option, no sidetext.\n";
-//!         std::cerr << "field parent is not null?: " << (field->parent != nullptr) << "\n";
+	auto sizer = new wxBoxSizer(wxHORIZONTAL);
+	grid_sizer->Add(sizer, 0, wxEXPAND | wxALL, 0);
+	if (option_set.size() == 1 && option_set.front().opt.sidetext.size() == 0 &&
+		option_set.front().side_widget == nullptr && line.get_extra_widgets().size() == 0) {
+		const auto& option = option_set.front();
+		const auto& field = build_field(option, label);
 
-        if (is_window_field(field)) 
-			grid_sizer->Add(field->getWindow(), 0, (option.opt.full_width ? wxEXPAND : 0) |
+		sizer->Add(field->m_Undo_btn, 0, wxALIGN_CENTER_VERTICAL);
+		if (is_window_field(field)) 
+			sizer->Add(field->getWindow(), 0, (option.opt.full_width ? wxEXPAND : 0) |
 							wxBOTTOM | wxTOP | wxALIGN_CENTER_VERTICAL, wxOSX ? 0 : 2);
-        if (is_sizer_field(field)) 
-            grid_sizer->Add(field->getSizer(), 0, (option.opt.full_width ? wxEXPAND : 0) | wxALIGN_CENTER_VERTICAL, 0);
-        return;
-    }
+		if (is_sizer_field(field)) 
+			sizer->Add(field->getSizer(), 0, (option.opt.full_width ? wxEXPAND : 0) | wxALIGN_CENTER_VERTICAL, 0);
+		return;
+	}
 
     // if we're here, we have more than one option or a single option with sidetext
     // so we need a horizontal sizer to arrange these things
-    auto sizer = new wxBoxSizer(wxHORIZONTAL);
-	grid_sizer->Add(sizer, 0, wxEXPAND | wxALL, 0);
 	for (auto opt : option_set) {
 		ConfigOptionDef option = opt.opt;
 		// add label if any
@@ -162,14 +162,15 @@ void OptionsGroup::append_line(const Line& line) {
 // 			wxString str_label = (option.label == "Top" || option.label == "Bottom") ?
 // 								wxGETTEXT_IN_CONTEXT("Layers", wxString(option.label.c_str()):
 // 								L_str(option.label);
-			/*auto field_*/label = new wxStaticText(parent(), wxID_ANY, str_label + ":", wxDefaultPosition, wxDefaultSize);
-			/*field_*/label->SetFont(label_font);
-			sizer->Add(/*field_*/label, 0, wxALIGN_CENTER_VERTICAL, 0);
+			label = new wxStaticText(parent(), wxID_ANY, str_label + ":", wxDefaultPosition, wxDefaultSize);
+			label->SetFont(label_font);
+			sizer->Add(label, 0, wxALIGN_CENTER_VERTICAL, 0);
 		}
 
 		// add field
 		const Option& opt_ref = opt;
 		auto& field = build_field(opt_ref, label);
+		sizer->Add(field->m_Undo_btn, 0, wxALIGN_CENTER_VERTICAL, 0);
 		is_sizer_field(field) ? 
 			sizer->Add(field->getSizer(), 0, wxALIGN_CENTER_VERTICAL, 0) :
 			sizer->Add(field->getWindow(), 0, wxALIGN_CENTER_VERTICAL, 0);
diff --git a/xs/src/slic3r/GUI/PresetHints.cpp b/xs/src/slic3r/GUI/PresetHints.cpp
index 07c8e3b07..d4c929c1c 100644
--- a/xs/src/slic3r/GUI/PresetHints.cpp
+++ b/xs/src/slic3r/GUI/PresetHints.cpp
@@ -13,10 +13,11 @@
 
 namespace Slic3r {
 
+#define MIN_BUF_LENGTH	4096
 std::string PresetHints::cooling_description(const Preset &preset)
 {
 	std::string out;
-	char buf[4096];
+	char buf[MIN_BUF_LENGTH/*4096*/];
 	if (preset.config.opt_bool("cooling", 0)) {
 		int 	slowdown_below_layer_time 	= preset.config.opt_int("slowdown_below_layer_time", 0);
 		int 	min_fan_speed 				= preset.config.opt_int("min_fan_speed", 0);
@@ -220,7 +221,7 @@ std::string PresetHints::maximum_volumetric_flow_description(const PresetBundle
             + _CHB(L(" with a volumetric rate "));
         if (limited_by_max_volumetric_speed)
             max_flow = max_volumetric_speed;
-        char buf[2048];
+		char buf[MIN_BUF_LENGTH/*2048*/];
         sprintf(buf, _CHB(L("%3.2f mm³/s")), max_flow);
         out += buf;
         sprintf(buf, _CHB(L(" at filament speed %3.2f mm/s.")), max_flow / filament_crossection);
@@ -258,7 +259,7 @@ std::string PresetHints::recommended_thin_wall_thickness(const PresetBundle &pre
     
     if (num_perimeters > 0) {
         int num_lines = std::min(num_perimeters * 2, 10);
-        char buf[256];
+		char buf[MIN_BUF_LENGTH/*256*/];
         sprintf(buf, _CHB(L("Recommended object thin wall thickness for layer height %.2f and ")), layer_height);
         out += buf;
         // Start with the width of two closely spaced 
diff --git a/xs/src/slic3r/GUI/Tab.cpp b/xs/src/slic3r/GUI/Tab.cpp
index 15fc5f006..aa30a655c 100644
--- a/xs/src/slic3r/GUI/Tab.cpp
+++ b/xs/src/slic3r/GUI/Tab.cpp
@@ -33,19 +33,23 @@ void Tab::create_preset_tab(PresetBundle *preset_bundle)
 
 	// preset chooser
 	m_presets_choice = new wxBitmapComboBox(panel, wxID_ANY, "", wxDefaultPosition, wxSize(270, -1), 0, 0,wxCB_READONLY);
-	const wxBitmap* bmp = new wxBitmap(from_u8(Slic3r::var("flag-green-icon.png")), wxBITMAP_TYPE_PNG);
+
+	auto color = wxSystemSettings::GetColour(wxSYS_COLOUR_WINDOW);
 
 	//buttons
 	wxBitmap bmpMenu;
 	bmpMenu = wxBitmap(from_u8(Slic3r::var("disk.png")), wxBITMAP_TYPE_PNG);
 	m_btn_save_preset = new wxBitmapButton(panel, wxID_ANY, bmpMenu, wxDefaultPosition, wxDefaultSize, wxBORDER_NONE);
+	m_btn_save_preset->SetBackgroundColour(color);
 	bmpMenu = wxBitmap(from_u8(Slic3r::var("delete.png")), wxBITMAP_TYPE_PNG);
 	m_btn_delete_preset = new wxBitmapButton(panel, wxID_ANY, bmpMenu, wxDefaultPosition, wxDefaultSize, wxBORDER_NONE);
+	m_btn_delete_preset->SetBackgroundColour(color);
 
 	m_show_incompatible_presets = false;
 	m_bmp_show_incompatible_presets = new wxBitmap(from_u8(Slic3r::var("flag-red-icon.png")), wxBITMAP_TYPE_PNG);
 	m_bmp_hide_incompatible_presets = new wxBitmap(from_u8(Slic3r::var("flag-green-icon.png")), wxBITMAP_TYPE_PNG);
 	m_btn_hide_incompatible_presets = new wxBitmapButton(panel, wxID_ANY, *m_bmp_hide_incompatible_presets, wxDefaultPosition, wxDefaultSize, wxBORDER_NONE);
+	m_btn_hide_incompatible_presets->SetBackgroundColour(color);
 
 	m_btn_save_preset->SetToolTip(_(L("Save current ")) + m_title);
 	m_btn_delete_preset->SetToolTip(_(L("Delete this preset")));
@@ -140,12 +144,34 @@ void Tab::update_dirty(){
 	m_presets->update_dirty_ui(m_presets_choice);
 	on_presets_changed();
 	auto dirty_options = m_presets->current_dirty_options();
+	// Add new dirty options to m_dirty_options
 	for (auto opt_key : dirty_options){
-		if (find(m_dirty_options.begin(), m_dirty_options.end(), opt_key) == m_dirty_options.end()){
-			get_field(opt_key)->m_Label->SetBackgroundColour(*get_modified_label_clr());
+		Field* field = get_field(opt_key/*, opt_index*/);
+		if (field != nullptr && find(m_dirty_options.begin(), m_dirty_options.end(), opt_key) == m_dirty_options.end()){
+			field->m_Label->SetForegroundColour(*get_modified_label_clr()); 
+			field->m_Undo_btn->Show();
+
 			m_dirty_options.push_back(opt_key);
 		}
 	}
+
+	// Delete undirty options from m_dirty_options
+	size_t cnt = m_dirty_options.size();
+	for (auto i = 0; i < /*cnt*/m_dirty_options.size(); ++i)
+	{
+		const std::string &opt_key = m_dirty_options[i];
+		Field* field = get_field(opt_key/*, opt_index*/);
+		if (field != nullptr && find(dirty_options.begin(), dirty_options.end(), opt_key) == dirty_options.end())
+		{		
+			field->m_Undo_btn->Hide();
+			field->m_Label->SetForegroundColour(wxSYS_COLOUR_WINDOWTEXT);
+			std::vector<std::string>::iterator itr = find(m_dirty_options.begin(), m_dirty_options.end(), opt_key);
+			if (itr != m_dirty_options.end()){
+				m_dirty_options.erase(itr);
+				--i;
+			}
+		}
+	}
 }
 
 void Tab::update_tab_ui()
@@ -947,7 +973,7 @@ void TabPrinter::build()
 
 		Line line{ _(L("Bed shape")), "" };
 		line.widget = [this](wxWindow* parent){
-	auto btn = new wxButton(parent, wxID_ANY, _(L(" Set "))+"\u2026", wxDefaultPosition, wxDefaultSize, wxBU_LEFT | wxBU_EXACTFIT);
+			auto btn = new wxButton(parent, wxID_ANY, _(L(" Set "))+"\u2026", wxDefaultPosition, wxDefaultSize, wxBU_LEFT | wxBU_EXACTFIT);
 			//			btn->SetFont(Slic3r::GUI::small_font);
 			btn->SetBitmap(wxBitmap(from_u8(Slic3r::var("printer_empty.png")), wxBITMAP_TYPE_PNG));