diff --git a/lib/Slic3r/GUI.pm b/lib/Slic3r/GUI.pm
index 88e8b072a..eb5a7bd01 100644
--- a/lib/Slic3r/GUI.pm
+++ b/lib/Slic3r/GUI.pm
@@ -5,7 +5,9 @@ use utf8;
 
 use File::Basename qw(basename);
 use FindBin;
-use List::Util qw(first);
+use List::Util qw(first any);
+use Slic3r::Geometry qw(X Y);
+
 use Slic3r::GUI::2DBed;
 use Slic3r::GUI::AboutDialog;
 use Slic3r::GUI::BedShapeDialog;
@@ -98,7 +100,7 @@ sub OnInit {
     Slic3r::debugf "wxWidgets version %s, Wx version %s\n", &Wx::wxVERSION_STRING, $Wx::VERSION;
     
     $self->{notifier} = Slic3r::GUI::Notifier->new;
-    $self->{external_presets} = [];
+    $self->{presets} = { print => [], filament => [], printer => [] };
     
     # locate or create data directory
     # Unix: ~/.Slic3r
@@ -142,6 +144,8 @@ sub OnInit {
         unlink "$enc_datadir/simple.ini";
     }
     
+    $self->load_presets;
+    
     # application frame
     Wx::Image::AddHandler(Wx::PNGHandler->new);
     $self->{mainframe} = my $frame = Slic3r::GUI::MainFrame->new(
@@ -283,47 +287,64 @@ sub save_settings {
     Slic3r::Config->write_ini("$datadir/slic3r.ini", $Settings);
 }
 
-sub presets {
-    my ($self, $section, $force_default) = @_;
+sub presets { return $_[0]->{presets}; }
+
+sub load_presets {
+    my ($self) = @_;
     
-    my @presets = ();
+    for my $group (qw(printer filament print)) {
+        my $presets = $self->{presets}{$group};
+        
+        # keep external or dirty presets
+        @$presets = grep { ($_->external && $_->file_exists) || $_->dirty } @$presets;
+        
+        my $dir = "$Slic3r::GUI::datadir/$group";
+        opendir my $dh, Slic3r::encode_path($dir)
+            or die "Failed to read directory $dir (errno: $!)\n";
+        foreach my $file (grep /\.ini$/i, readdir $dh) {
+            $file = Slic3r::decode_path($file);
+            my $name = basename($file);
+            $name =~ s/\.ini$//i;
+            
+            # skip if we already have it
+            next if any { $_->name eq $name } @$presets;
+            
+            push @$presets, Slic3r::GUI::Preset->new(
+                group   => $group,
+                name    => $name,
+                file    => "$dir/$file",
+            );
+        }
+        closedir $dh;
     
-    opendir my $dh, Slic3r::encode_path("$Slic3r::GUI::datadir/$section")
-        or die "Failed to read directory $Slic3r::GUI::datadir/$section (errno: $!)\n";
-    foreach my $file (grep /\.ini$/i, readdir $dh) {
-        $file = Slic3r::decode_path($file);
-        my $name = basename($file);
-        $name =~ s/\.ini$//i;
-        push @presets, Slic3r::GUI::Preset->new(
-            name => $name,
-            file => "$Slic3r::GUI::datadir/$section/$file",
-        );
-    }
-    closedir $dh;
+        @$presets = sort { $a->name cmp $b->name } @$presets;
     
-    @presets = sort { $a->name cmp $b->name }
-        @presets,
-        (grep -e $_->file, @{$self->{external_presets}});
-    
-    if ($force_default || !@presets) {
-        unshift @presets, Slic3r::GUI::Preset->new(
+        unshift @$presets, Slic3r::GUI::Preset->new(
+            group   => $group,
             default => 1,
             name    => '- default -',
         );
     }
-    
-    return @presets;
 }
 
 sub add_external_preset {
     my ($self, $file) = @_;
     
-    push @{$self->{external_presets}}, my $preset = Slic3r::GUI::Preset->new(
-        name     => basename($file),  # keep .ini suffix
-        file     => $file,
-        external => 1,
-    );
-    return $preset;
+    my $name = basename($file);  # keep .ini suffix
+    for my $group (qw(printer filament print)) {
+        my $presets = $self->{presets}{$group};
+        
+        # remove any existing preset with the same name
+        @$presets = grep { $_->name ne $name } @$presets;
+        
+        push @$presets, Slic3r::GUI::Preset->new(
+            group    => $group,
+            name     => $name,
+            file     => $file,
+            external => 1,
+        );
+    }
+    return $name;
 }
 
 sub have_version_check {
@@ -416,4 +437,29 @@ sub set_menu_item_icon {
     }
 }
 
+sub save_window_pos {
+    my ($self, $window, $name) = @_;
+    
+    $Settings->{_}{"${name}_pos"}  = join ',', $window->GetScreenPositionXY;
+    $Settings->{_}{"${name}_size"} = join ',', $window->GetSizeWH;
+    $Settings->{_}{"${name}_maximized"}      = $window->IsMaximized;
+    $self->save_settings;
+}
+
+sub restore_window_pos {
+    my ($self, $window, $name) = @_;
+    
+    if (defined $Settings->{_}{"${name}_pos"}) {
+        my $size = [ split ',', $Settings->{_}{"${name}_size"}, 2 ];
+        $window->SetSize($size);
+        
+        my $display = Wx::Display->new->GetClientArea();
+        my $pos = [ split ',', $Settings->{_}{"${name}_pos"}, 2 ];
+        if (($pos->[X] + $size->[X]/2) < $display->GetRight && ($pos->[Y] + $size->[Y]/2) < $display->GetBottom) {
+            $window->Move($pos);
+        }
+        $window->Maximize(1) if $Settings->{_}{"${name}_maximized"};
+    }
+}
+
 1;
diff --git a/lib/Slic3r/GUI/Controller.pm b/lib/Slic3r/GUI/Controller.pm
index 7ebf3491d..87b85fde2 100644
--- a/lib/Slic3r/GUI/Controller.pm
+++ b/lib/Slic3r/GUI/Controller.pm
@@ -47,7 +47,7 @@ sub new {
             delete $presets{$_} for map $_->printer_name, @panels;
             
             foreach my $preset_name (sort keys %presets) {
-                my $config = $presets{$preset_name}->load_config;
+                my $config = $presets{$preset_name}->dirty_config;
                 next if !$config->serial_port;
                 
                 my $id = &Wx::NewId();
@@ -101,7 +101,7 @@ sub OnActivate {
     # get all available presets
     my %presets = ();
     {
-        my %all = map { $_->name => $_ } wxTheApp->presets('printer');
+        my %all = map { $_->name => $_ } @{wxTheApp->presets->{printer}};
         my %configs = map { my $name = $_; $name => $all{$name}->load_config } keys %all;
         %presets = map { $_ => $configs{$_} } grep $configs{$_}->serial_port, keys %all;
     }
diff --git a/lib/Slic3r/GUI/MainFrame.pm b/lib/Slic3r/GUI/MainFrame.pm
index 9a6707b91..7b21d64c3 100644
--- a/lib/Slic3r/GUI/MainFrame.pm
+++ b/lib/Slic3r/GUI/MainFrame.pm
@@ -56,19 +56,8 @@ sub new {
         $self->SetSizer($sizer);
         $self->Fit;
         $self->SetMinSize([760, 490]);
-        if (defined $Slic3r::GUI::Settings->{_}{main_frame_size}) {
-            my $size = [ split ',', $Slic3r::GUI::Settings->{_}{main_frame_size}, 2 ];
-            $self->SetSize($size);
-            
-            my $display = Wx::Display->new->GetClientArea();
-            my $pos = [ split ',', $Slic3r::GUI::Settings->{_}{main_frame_pos}, 2 ];
-            if (($pos->[X] + $size->[X]/2) < $display->GetRight && ($pos->[Y] + $size->[Y]/2) < $display->GetBottom) {
-                $self->Move($pos);
-            }
-            $self->Maximize(1) if $Slic3r::GUI::Settings->{_}{main_frame_maximized};
-        } else {
-            $self->SetSize($self->GetMinSize);
-        }
+        $self->SetSize($self->GetMinSize);
+        wxTheApp->restore_window_pos($self, "main_frame");
         $self->Show;
         $self->Layout;
     }
@@ -78,23 +67,23 @@ sub new {
         my (undef, $event) = @_;
         
         if ($event->CanVeto) {
-            my $veto = 0;
+            if (!$self->{plater}->prompt_unsaved_changes) {
+                $event->Veto;
+                return;
+            }
+            
             if ($self->{controller} && $self->{controller}->printing) {
                 my $confirm = Wx::MessageDialog->new($self, "You are currently printing. Do you want to stop printing and continue anyway?",
                     'Unfinished Print', wxICON_QUESTION | wxYES_NO | wxNO_DEFAULT);
-                $veto = 1 if $confirm->ShowModal == wxID_YES;
-            }
-            if ($veto) {
-                $event->Veto;
-                return;
+                if ($confirm->ShowModal == wxID_NO) {
+                    $event->Veto;
+                    return;
+                }
             }
         }
         
         # save window size
-        $Slic3r::GUI::Settings->{_}{main_frame_pos}  = join ',', $self->GetScreenPositionXY;
-        $Slic3r::GUI::Settings->{_}{main_frame_size} = join ',', $self->GetSizeWH;
-        $Slic3r::GUI::Settings->{_}{main_frame_maximized} = $self->IsMaximized;
-        wxTheApp->save_settings;
+        wxTheApp->save_window_pos($self, "main_frame");
         
         # propagate event
         $event->Skip;
@@ -507,9 +496,9 @@ sub load_config_file {
     wxTheApp->save_settings;
     $last_config = $file;
     
-    my $preset = wxTheApp->add_external_preset($file);
+    my $name = wxTheApp->add_external_preset($file);
     $self->{plater}->load_presets;
-    $self->{plater}->select_preset_by_name($preset->name, $_) for qw(print filament printer);
+    $self->{plater}->select_preset_by_name($name, $_) for qw(print filament printer);
 }
 
 sub export_configbundle {
@@ -536,8 +525,9 @@ sub export_configbundle {
         $ini->{presets} = $Slic3r::GUI::Settings->{presets};
         
         foreach my $section (qw(print filament printer)) {
-            my @presets = wxTheApp->presets($section);
+            my @presets = @{wxTheApp->presets->{$section}};
             foreach my $preset (@presets) {
+                next if $preset->default || $preset->external;
                 $ini->{"$section:" . $preset->name} = $preset->load_config->as_ini->{_};
             }
         }
@@ -581,10 +571,10 @@ sub load_configbundle {
         next if $skip_no_id && !$config->get($section . "_settings_id");
         
         {
-            my @current_presets = Slic3r::GUI->presets($section);
+            my @current_presets = @{wxTheApp->presets->{$section}};
             my %current_ids = map { $_ => 1 }
                 grep $_,
-                map $_->load_config->get($section . "_settings_id"),
+                map $_->dirty_config->get($section . "_settings_id"),
                 @current_presets;
             next INI_BLOCK if exists $current_ids{$config->get($section . "_settings_id")};
         }
diff --git a/lib/Slic3r/GUI/Plater.pm b/lib/Slic3r/GUI/Plater.pm
index 21c98bf78..f586c7b43 100644
--- a/lib/Slic3r/GUI/Plater.pm
+++ b/lib/Slic3r/GUI/Plater.pm
@@ -368,6 +368,7 @@ sub new {
             printer     => 'Printer',
         );
         $self->{preset_choosers} = {};
+        $self->{preset_choosers_names} = {};  # wxChoice* => []
         for my $group (qw(print filament printer)) {
             # label
             my $text = Wx::StaticText->new($self, -1, "$group_labels{$group}:", wxDefaultPosition, wxDefaultSize, wxALIGN_RIGHT);
@@ -380,7 +381,7 @@ sub new {
             EVT_COMBOBOX($choice, $choice, sub {
                 my ($choice) = @_;
                 wxTheApp->CallAfter(sub {
-                    $self->_on_select_preset($group);
+                    $self->_on_change_combobox($group, $choice);
                 });
             });
             
@@ -512,11 +513,52 @@ sub new {
     return $self;
 }
 
+sub prompt_unsaved_changes {
+    my ($self) = @_;
+    
+    foreach my $group (qw(printer filament print)) {
+        foreach my $choice (@{$self->{preset_choosers}{$group}}) {
+            my $pp = $self->{preset_choosers_names}{$choice};
+            for my $i (0..$#$pp) {
+                my $preset = first { $_->name eq $pp->[$i] } @{wxTheApp->presets->{$group}};
+                if (!$preset->prompt_unsaved_changes($self)) {
+                    # Restore the previous one
+                    $choice->SetSelection($i);
+                    return 0;
+                }
+            }
+        }
+    }
+    return 1;
+}
+
+sub _on_change_combobox {
+    my ($self, $group, $choice) = @_;
+    
+    if (0) {
+        # This code is disabled because wxPerl doesn't provide GetCurrentSelection
+        my $current_name = $self->{preset_choosers_names}{$choice}[$choice->GetCurrentSelection];
+        my $current = first { $_->name eq $current_name } @{wxTheApp->presets->{$group}};
+        if (!$current->prompt_unsaved_changes($self)) {
+            # Restore the previous one
+            $choice->SetSelection($choice->GetCurrentSelection);
+            return;
+        }
+    } else {
+        return 0 if !$self->prompt_unsaved_changes;
+    }
+    wxTheApp->CallAfter(sub {
+        $self->_on_select_preset($group);
+        
+        # This will remove the "(modified)" mark from any dirty preset handled here.
+        $self->load_presets;
+    });
+}
+
 sub _on_select_preset {
 	my ($self, $group) = @_;
 	
-    my @presets = map $self->presets->{$group}[scalar $_->GetSelection], 
-        @{$self->{preset_choosers}{$group}};
+	my @presets = $self->selected_presets($group);
     
     $Slic3r::GUI::Settings->{presets}{$group} = $presets[0]->name;
     $Slic3r::GUI::Settings->{presets}{"${group}_${_}"} = $presets[$_]->name
@@ -565,17 +607,16 @@ sub GetFrame {
 sub load_presets {
     my ($self) = @_;
     
-    $self->presets({});
-    
     my $selected_printer_name;
     foreach my $group (qw(printer filament print)) {
-        my @presets = wxTheApp->presets($group);
+        my @presets = @{wxTheApp->presets->{$group}};
+        
+        # Skip presets not compatible with the selected printer, if they
+        # have other compatible printers configured (and at least one of them exists).
         if ($group eq 'filament' || $group eq 'print') {
-            my %printer_names = map { $_->name => 1 } @{ $self->presets->{printer} };
-            # Skip presets not compatible with the selected printer, if they
-            # have other compatible printers configured (and at least one of them exists).
+            my %printer_names = map { $_->name => 1 } @{ wxTheApp->presets->{printer} };
             for (my $i = 0; $i <= $#presets; ++$i) {
-                my $config = $presets[$i]->config;
+                my $config = $presets[$i]->dirty_config;
                 next if !$config->has('compatible_printers');
                 my @compat = @{$config->compatible_printers};
                 if (@compat
@@ -586,14 +627,11 @@ sub load_presets {
                 }
             }
         }
-        if (!@presets) {
-            unshift @presets, Slic3r::GUI::Preset->new(
-                default => 1,
-                name    => '- default -',
-            );
-        }
         
-        $self->presets->{$group} = [@presets];
+        # Only show the default presets if we have no other presets.
+        if (@presets > 1) {
+            @presets = grep { !$_->default } @presets;
+        }
         
         # get the wxChoice objects for this group
         my @choosers = @{ $self->{preset_choosers}{$group} };
@@ -613,11 +651,12 @@ sub load_presets {
         # populate the wxChoice objects
         foreach my $choice (@choosers) {
             $choice->Clear;
+            $self->{preset_choosers_names}{$choice} = [];
             foreach my $preset (@presets) {
                 # load/generate the proper icon
                 my $bitmap;
                 if ($group eq 'filament') {
-                    my $config = $preset->config;
+                    my $config = $preset->dirty_config;
                     if ($preset->default || !$config->has('filament_colour')) {
                         $bitmap = Wx::Bitmap->new($Slic3r::var->("spool.png"), wxBITMAP_TYPE_PNG);
                     } else {
@@ -634,7 +673,8 @@ sub load_presets {
                 } elsif ($group eq 'printer') {
                     $bitmap = Wx::Bitmap->new($Slic3r::var->("printer_empty.png"), wxBITMAP_TYPE_PNG);
                 }
-                $choice->AppendString($preset->name, $bitmap);
+                $choice->AppendString($preset->dropdown_name, $bitmap);
+                push @{$self->{preset_choosers_names}{$choice}}, $preset->name;
             }
             
             my $selected = shift @sel;
@@ -643,14 +683,13 @@ sub load_presets {
                 # won't be picked up as the visible string
                 $choice->SetSelection($selected);
                 
-                my $preset_name = $choice->GetString($selected);
+                my $preset_name = $self->{preset_choosers_names}{$choice}[$selected];
                 $self->{print}->placeholder_parser->set("${group}_preset", $preset_name);
+                # TODO: populate other filament preset placeholders
                 $selected_printer_name = $preset_name if $group eq 'printer';
             }
         }
     }
-    
-    #$self->_on_select_preset($_) for qw(printer filament print);
 }
 
 sub select_preset_by_name {
@@ -658,11 +697,12 @@ sub select_preset_by_name {
     
     # $n is optional
     
-    my $presets = $self->presets->{$group};
-    my $i = first { $presets->[$_]->name eq $name } 0..$#$presets;
+    my $presets = wxTheApp->presets->{$group};
+    my $choosers = $self->{preset_choosers}{$group};
+    my $names = $self->{preset_choosers_names}{$choosers->[0]};
+    my $i = first { $names->[$_] eq $name } 0..$#$names;
     return if !defined $i;
     
-    my $choosers = $self->{preset_choosers}{$group};
     if (defined $n && $n <= $#$choosers) {
         $choosers->[$n]->SetSelection($i);
     } else {
@@ -674,10 +714,16 @@ sub select_preset_by_name {
 sub selected_presets {
     my ($self, $group) = @_;
     
-    my %presets;
+    my %presets = ();
     foreach my $group (qw(printer filament print)) {
-        my @i = map scalar($_->GetSelection), @{ $self->{preset_choosers}{$group} };
-        $presets{$group} = [ @{$self->presets->{$group}}[@i] ];
+        $presets{$group} = [];
+        foreach my $choice (@{$self->{preset_choosers}{$group}}) {
+            my $sel = $choice->GetSelection;
+            $sel = 0 if $sel == -1;
+            push @{ $presets{$group} },
+                grep { $_->name eq $self->{preset_choosers_names}{$choice}[$sel] }
+                @{wxTheApp->presets->{$group}};
+        }
     }
     return $group ? @{$presets{$group}} : %presets;
 }
@@ -697,7 +743,7 @@ sub show_preset_editor {
     
     # Select the preset that was last selected in the editor.
     $self->select_preset_by_name
-        ($dlg->preset_editor->get_current_preset->name, $group, $i, 1);
+        ($dlg->preset_editor->current_preset->name, $group, $i, 1);
 }
 
 # Returns the current config by merging the selected presets and the overrides.
@@ -715,16 +761,13 @@ sub config {
         qw(print filament printer);
     
     my %presets = $self->selected_presets;
-    $config->apply($_->config([ $classes{printer}->options ]))
-        for @{ $presets{printer} };
+    $config->apply($_->dirty_config) for @{ $presets{printer} };
     if (@{ $presets{filament} }) {
-        my @opt_keys = ($classes{filament}->options, $classes{filament}->overriding_options);
-        my $filament_config = shift(@{ $presets{filament} })
-            ->config(\@opt_keys);
+        my $filament_config = $presets{filament}[0]->dirty_config;
         
-        my $i = 1;
-        for my $preset (@{ $presets{filament} }) {
-            my $config = $preset->config(\@opt_keys);
+        for my $i (1..$#{ $presets{filament} }) {
+            my $preset = $presets{filament}[$i];
+            my $config = $preset->dirty_config;
             foreach my $opt_key (@{$config->get_keys}) {
                 if ($filament_config->has($opt_key)) {
                     my $value = $filament_config->get($opt_key);
@@ -733,14 +776,11 @@ sub config {
                     $filament_config->set($opt_key, $value);
                 }
             }
-            ++$i;
         }
         
         $config->apply($filament_config);
     }
-    $config->apply($_->config([ $classes{print}->options ]))
-        for @{ $presets{print} };
-    
+    $config->apply($_->dirty_config) for @{ $presets{print} };
     $config->apply($self->{settings_override_config});
     
     return $config;
@@ -1896,7 +1936,7 @@ sub on_extruders_change {
         EVT_COMBOBOX($choice, $choice, sub {
             my ($choice) = @_;
             wxTheApp->CallAfter(sub {
-                $self->_on_select_preset('filament');
+                $self->_on_change_combobox('filament', $choice);
             });
         });
         
diff --git a/lib/Slic3r/GUI/Plater/OverrideSettingsPanel.pm b/lib/Slic3r/GUI/Plater/OverrideSettingsPanel.pm
index 9549807a8..781e0fb6d 100644
--- a/lib/Slic3r/GUI/Plater/OverrideSettingsPanel.pm
+++ b/lib/Slic3r/GUI/Plater/OverrideSettingsPanel.pm
@@ -71,7 +71,7 @@ sub new {
                 EVT_MENU($menu, $id, sub {
                     $self->{config}->set($opt_key, $self->{default_config}->get($opt_key));
                     $self->update_optgroup;
-                    $self->{on_change}->() if $self->{on_change};
+                    $self->{on_change}->($opt_key) if $self->{on_change};
                 });
             }
             $self->PopupMenu($menu, $btn->GetPosition);
@@ -155,7 +155,10 @@ sub update_optgroup {
             label_font      => $Slic3r::GUI::small_font,
             sidetext_font   => $Slic3r::GUI::small_font,
             label_width     => 120,
-            on_change       => sub { $self->{on_change}->() if $self->{on_change} },
+            on_change       => sub {
+                my ($opt_key) = @_;
+                $self->{on_change}->($opt_key) if $self->{on_change};
+            },
             extra_column    => sub {
                 my ($line) = @_;
                 
@@ -169,7 +172,7 @@ sub update_optgroup {
                     wxDefaultPosition, wxDefaultSize, Wx::wxBORDER_NONE);
                 EVT_BUTTON($self, $btn, sub {
                     $self->{config}->erase($opt_key);
-                    $self->{on_change}->() if $self->{on_change};
+                    $self->{on_change}->($opt_key) if $self->{on_change};
                     wxTheApp->CallAfter(sub { $self->update_optgroup });
                 });
                 return $btn;
diff --git a/lib/Slic3r/GUI/Preset.pm b/lib/Slic3r/GUI/Preset.pm
index d855c3c60..5bdd0f20e 100644
--- a/lib/Slic3r/GUI/Preset.pm
+++ b/lib/Slic3r/GUI/Preset.pm
@@ -1,11 +1,16 @@
 package Slic3r::GUI::Preset;
 use Moo;
-use Unicode::Normalize;
 
+use Unicode::Normalize;
+use Wx qw(:dialog :icon :id wxTheApp);
+
+has 'group'     => (is => 'ro', required => 1);
 has 'default'   => (is => 'ro', default => sub { 0 });
 has 'external'  => (is => 'ro', default => sub { 0 });
 has 'name'      => (is => 'rw', required => 1);
 has 'file'      => (is => 'rw');
+has '_config'   => (is => 'rw', default => sub { Slic3r::Config->new });
+has '_dirty_config' => (is => 'ro', default => sub { Slic3r::Config->new });
 
 sub BUILD {
     my ($self) = @_;
@@ -13,40 +18,193 @@ sub BUILD {
     $self->name(Unicode::Normalize::NFC($self->name));
 }
 
-sub config {
-    my ($self, $keys, $extra_keys) = @_;
+sub _loaded {
+    my ($self) = @_;
     
-    if ($self->default) {
-        return Slic3r::Config->new_from_defaults(@$keys);
-    } else {
-        if (!-e Slic3r::encode_path($self->file)) {
-            Slic3r::GUI::show_error(undef, "The selected preset does not exist anymore (" . $self->file . ").");
-            return undef;
-        }
-        my $external_config = $self->load_config;
-        if (!$keys) {
-            return $external_config;
-        } else {
-            # apply preset values on top of defaults
-            my $config = Slic3r::Config->new_from_defaults(@$keys);
-            $config->set($_, $external_config->get($_))
-                for grep $external_config->has($_), @$keys;
-            
-            # For extra_keys we don't populate defaults.
-            if ($extra_keys && !$self->external) {
-                $config->set($_, $external_config->get($_))
-                    for grep $external_config->has($_), @$extra_keys;
-            }
+    return !$self->_config->empty;
+}
+
+sub dirty_options {
+    my ($self) = @_;
+    
+    my @dirty = ();
+    
+    # Options present in both configs with different values:
+    push @dirty, @{$self->_config->diff($self->_dirty_config)};
+    
+    # Overrides added to the dirty config:
+    my @extra = $self->_group_class->overriding_options;
+    push @dirty, grep { !$self->_config->has($_) && $self->_dirty_config->has($_) } @extra;
+    # Overrides removed from the dirty config:
+    push @dirty, grep { $self->_config->has($_) && !$self->_dirty_config->has($_) } @extra;
+    
+    return @dirty;
+}
+
+sub dirty {
+    my ($self) = @_;
+    
+    return !!$self->dirty_options;
+}
+
+sub dropdown_name {
+    my ($self) = @_;
+    
+    my $name = $self->name;
+    $name .= " (modified)" if $self->dirty;
+    return $name;
+}
+
+sub file_exists {
+    my ($self) = @_;
+    
+    die "Can't call file_exists() on a non-file preset" if !$self->file;
+    return -e Slic3r::encode_path($self->file);
+}
+
+sub rename {
+    my ($self, $name) = @_;
+    
+    $self->name($name);
+    $self->file(sprintf "$Slic3r::GUI::datadir/%s/%s.ini", $self->group, $name);
+}
+
+sub prompt_unsaved_changes {
+    my ($self, $parent) = @_;
+    
+    if ($self->dirty) {
+        my $name = $self->default ? 'Default preset' : "Preset \"" . $self->name . "\"";
         
-            return $config;
+        my $opts = '';
+        foreach my $opt_key ($self->dirty_options) {
+            my $opt = $Slic3r::Config::Options->{$opt_key};
+            my $name = $opt->{full_label} // $opt->{label};
+            if ($opt->{category}) {
+                $name = $opt->{category} . " > $name";
+            }
+            $opts .= "- $name\n";
+        }
+        
+        my $msg = sprintf "%s has unsaved changes:\n%s\nDo you want to save them?", $name, $opts;
+        my $confirm = Wx::MessageDialog->new($parent, $msg,
+            'Unsaved Changes', wxYES_NO | wxCANCEL | wxYES_DEFAULT | wxICON_QUESTION);
+        $confirm->SetYesNoCancelLabels('Save', 'Discard', 'Cancel');
+        my $res = $confirm->ShowModal;
+        
+        if ($res == wxID_CANCEL) {
+            return 0;
+        } elsif ($res == wxID_YES) {
+            return $self->save($self->default ? undef : $self->name);
+        } elsif ($res == wxID_NO) {
+            $self->dismiss_changes;
+            return 1;
         }
     }
+    
+    return 1;
+}
+
+sub save {
+    my ($self, $name, $parent) = @_;
+    
+    if (!$name) {
+        my $default_name = $self->default ? 'Untitled' : $self->name;
+        $default_name =~ s/\.ini$//i;
+    
+        my $dlg = Slic3r::GUI::SavePresetWindow->new($parent,
+            default => $default_name,
+            values  => [ map $_->name, grep !$_->default && !$_->external, @{wxTheApp->presets->{$self->name}} ],
+        );
+        return 0 unless $dlg->ShowModal == wxID_OK;
+        $name = $dlg->get_name;
+    }
+    
+    $self->rename($name);
+    
+    if (!$self->file) {
+        die "Calling save() without setting filename";
+    }
+    
+    $self->_config->clear;
+    $self->_config->apply($self->_dirty_config);
+    $self->_config->save($self->file);
+    wxTheApp->load_presets;
+    
+    return 1;
+}
+
+sub dismiss_changes {
+    my ($self) = @_;
+    
+    $self->_dirty_config->clear;
+    $self->_dirty_config->apply($self->_config);
+}
+
+sub delete {
+    my ($self) = @_;
+    
+    die "Default config can't be deleted" if $self->default;
+    die "External configs can't be deleted" if $self->external;
+    
+    # Otherwise wxTheApp->load_presets() will keep it
+    $self->dismiss_changes;
+    
+    if ($self->file) {
+        unlink Slic3r::encode_path($self->file) if $self->file_exists;
+        $self->file(undef);
+    }
+}
+
+# This returns the loaded config with the dirty options applied.
+sub dirty_config {
+    my ($self) = @_;
+    
+    $self->load_config if !$self->_loaded;
+    
+    return $self->_dirty_config->clone;
 }
 
 sub load_config {
     my ($self) = @_;
     
-    return Slic3r::Config->load($self->file);
+    my @keys = $self->_group_class->options;
+    my @extra_keys = $self->_group_class->overriding_options;
+    
+    if ($self->default) {
+        $self->_config(Slic3r::Config->new_from_defaults(@keys));
+    } elsif ($self->file) {
+        if (!$self->file_exists) {
+            Slic3r::GUI::show_error(undef, "The selected preset does not exist anymore (" . $self->file . ").");
+            return undef;
+        }
+        my $external_config = Slic3r::Config->load($self->file);
+        if (!@keys) {
+            $self->_config($external_config);
+        } else {
+            # apply preset values on top of defaults
+            my $config = Slic3r::Config->new_from_defaults(@keys);
+            $config->set($_, $external_config->get($_))
+                for grep $external_config->has($_), @keys;
+            
+            # For extra_keys we don't populate defaults.
+            if (@extra_keys && !$self->external) {
+                $config->set($_, $external_config->get($_))
+                    for grep $external_config->has($_), @extra_keys;
+            }
+        
+            $self->_config($config);
+        }
+    }
+    
+    $self->_dirty_config->apply($self->_config);
+    
+    return $self->_config;
+}
+
+sub _group_class {
+    my ($self) = @_;
+    
+    return "Slic3r::GUI::PresetEditor::".ucfirst $self->group;
 }
 
 1;
diff --git a/lib/Slic3r/GUI/PresetEditor.pm b/lib/Slic3r/GUI/PresetEditor.pm
index 63bc52981..758810490 100644
--- a/lib/Slic3r/GUI/PresetEditor.pm
+++ b/lib/Slic3r/GUI/PresetEditor.pm
@@ -10,13 +10,15 @@ use Wx qw(:bookctrl :dialog :keycode :icon :id :misc :panel :sizer :treectrl :wi
 use Wx::Event qw(EVT_BUTTON EVT_CHOICE EVT_KEY_DOWN EVT_TREE_SEL_CHANGED);
 use base qw(Wx::Panel Class::Accessor);
 
-__PACKAGE__->mk_accessors(qw(current_preset));
+__PACKAGE__->mk_accessors(qw(current_preset config));
 
 sub new {
     my $class = shift;
     my ($parent, %params) = @_;
     my $self = $class->SUPER::new($parent, -1, wxDefaultPosition, wxDefaultSize, wxBK_LEFT | wxTAB_TRAVERSAL);
     
+    $self->{presets} = wxTheApp->presets->{$self->name};
+    
     # horizontal sizer
     $self->{sizer} = Wx::BoxSizer->new(wxHORIZONTAL);
     #$self->{sizer}->SetSizeHints($self);
@@ -91,78 +93,39 @@ sub new {
     EVT_BUTTON($self, $self->{btn_save_preset}, sub { $self->save_preset });
     
     EVT_BUTTON($self, $self->{btn_delete_preset}, sub {
-        my $i = $self->current_preset;
-        return if $i == 0;  # this shouldn't happen but let's trap it anyway
         my $res = Wx::MessageDialog->new($self, "Are you sure you want to delete the selected preset?", 'Delete Preset', wxYES_NO | wxNO_DEFAULT | wxICON_QUESTION)->ShowModal;
         return unless $res == wxID_YES;
-        if (-e $self->{presets}[$i]->file) {
-            unlink $self->{presets}[$i]->file;
-        }
-        splice @{$self->{presets}}, $i, 1;
-        $self->{presets_choice}->Delete($i);
+        
+        $self->current_preset->delete;
         $self->current_preset(undef);
-        $self->select_preset(0);
+        wxTheApp->load_presets;
+        $self->load_presets;
+        $self->select_preset(0, 1);
     });
     
-    # C++ instance DynamicPrintConfig
-    $self->{config} = Slic3r::Config->new;
-    # Initialize the DynamicPrintConfig by default keys/values.
-    $self->{config}->apply(Slic3r::Config->new_from_defaults($self->options));
+    $self->config(Slic3r::Config->new_from_defaults($self->options));
     
-    
-    
-    # Possible %params keys: no_controller
-    $self->build(%params);
+    $self->build;
     $self->update_tree;
+    $self->load_presets;
     $self->_update;
-    if ($self->hidden_options) {
-        $self->{config}->apply(Slic3r::Config->new_from_defaults($self->hidden_options));
-    }
     
     return $self;
 }
 
-sub get_current_preset {
-    my $self = shift;
-    return $self->get_preset($self->current_preset);
-}
-
-sub get_current_preset_config {
-    my ($self) = @_;
-    
-    return $self->get_preset_config($self->get_current_preset);
-}
-
-sub get_preset {
-    my ($self, $i) = @_;
-    return $self->{presets}[$i];
-}
-
+# This is called by the save button.
 sub save_preset {
-    my ($self, $name) = @_;
+    my ($self) = @_;
     
     # since buttons (and choices too) don't get focus on Mac, we set focus manually
     # to the treectrl so that the EVT_* events are fired for the input field having
     # focus currently. is there anything better than this?
     $self->{treectrl}->SetFocus;
     
-    if (!defined $name) {
-        my $preset = $self->get_current_preset;
-        my $default_name = $preset->default ? 'Untitled' : $preset->name;
-        $default_name =~ s/\.ini$//i;
-    
-        my $dlg = Slic3r::GUI::SavePresetWindow->new($self,
-            title   => lc($self->title),
-            default => $default_name,
-            values  => [ map $_->name, grep !$_->default && !$_->external, @{$self->{presets}} ],
-        );
-        return 0 unless $dlg->ShowModal == wxID_OK;
-        $name = $dlg->get_name;
-    }
-    
-    $self->config->save(sprintf "$Slic3r::GUI::datadir/%s/%s.ini", $self->name, $name);
+    my $preset = $self->current_preset;
+    $preset->save(undef, $self);
     $self->load_presets;
-    $self->select_preset_by_name($name);
+    $self->select_preset_by_name($preset->name);
     
     return 1;
 }
@@ -176,17 +139,17 @@ sub on_value_change {
 # or changed by user (so also when a preset is loaded).
 # propagate event to the parent
 sub _on_value_change {
-    my $self = shift;
+    my ($self, $opt_key) = @_;
     
-    $self->{on_value_change}->(@_) if $self->{on_value_change};
+    $self->current_preset->_dirty_config->apply($self->config);
+    $self->{on_value_change}->($opt_key) if $self->{on_value_change};
+    $self->load_presets;
     $self->_update;
 }
 
 sub _update {}
 
 sub on_preset_loaded {}
-sub hidden_options {}
-sub config { $_[0]->{config}->clone }
 
 sub select_preset {
     my ($self, $i, $force) = @_;
@@ -198,62 +161,54 @@ sub select_preset {
 sub select_preset_by_name {
     my ($self, $name, $force) = @_;
     
-    my $i = first { $self->{presets}[$_]->name eq $name } 0 .. $#{$self->{presets}};
-    return if !defined $i;
-    $self->select_preset($i, $force);
+    my $presets = wxTheApp->presets->{$self->name};
+    my $i = first { $presets->[$_]->name eq $name } 0..$#$presets;
+    $self->{presets_choice}->SetSelection($i);
+    $self->on_select_preset($force);
 }
 
 sub prompt_unsaved_changes {
     my ($self) = @_;
     
-    if ($self->is_dirty) {
-        my $old_preset = $self->get_current_preset;
-        my $name = $old_preset->default ? 'Default preset' : "Preset \"" . $old_preset->name . "\"";
-        
-        my @option_names = ();
-        foreach my $opt_key (@{$self->dirty_options}) {
-            my $opt = $Slic3r::Config::Options->{$opt_key};
-            my $name = $opt->{full_label} // $opt->{label};
-            if ($opt->{category}) {
-                $name = $opt->{category} . " > $name";
-            }
-            push @option_names, $name;
-        }
-        
-        my $changes = join "\n", map "- $_", @option_names;
-        my $confirm = Wx::MessageDialog->new($self, "$name has unsaved changes:\n$changes\n\nDo you want to save them?",
-            'Unsaved Changes', wxYES_NO | wxCANCEL | wxYES_DEFAULT | wxICON_QUESTION);
-        $confirm->SetYesNoCancelLabels('Save', 'Discard', 'Cancel');
-        my $res = $confirm->ShowModal;
-        
-        if ($res == wxID_CANCEL) {
-            return 0;
-        } elsif ($res == wxID_YES) {
-            return $self->save_preset($old_preset->default ? undef : $old_preset->name);
-        }
-    }
-    
-    return 1;
+    return 1 if !$self->current_preset;
+    return $self->current_preset->prompt_unsaved_changes($self);
 }
 
 sub on_select_preset {
     my ($self, $force) = @_;
     
-    my $i = $self->{presets_choice}->GetSelection;
-    return if defined $self->current_preset && $i == $self->current_preset;
+    # This method is called:
+    # - upon first initialization;
+    # - whenever user selects a preset from the dropdown;
+    # - whenever select_preset() or select_preset_by_name() are called.
     
-    if (!$force && defined $self->current_preset && !$self->prompt_unsaved_changes) {
-        $self->{presets_choice}->SetSelection($self->current_preset);
+    # Get the selected name.
+    my $preset = wxTheApp->presets->{$self->name}->[$self->{presets_choice}->GetSelection];
+    
+    # If selection didn't change, do nothing.
+    return if defined $self->current_preset && $preset->name eq $self->current_preset->name;
+    
+    # If we have unsaved changes, prompt user.
+    if (!$force && !$self->prompt_unsaved_changes) {
+        # User decided not to save the current changes, so we restore the previous selection.
+        my $presets = wxTheApp->presets->{$self->name};
+        my $i = first { $presets->[$_]->name eq $self->current_preset->name } 0..$#$presets;
+        $self->{presets_choice}->SetSelection($i);
         return;
     }
     
-    $self->current_preset($i);
-    my $preset = $self->get_current_preset;
-    my $preset_config = $self->get_preset_config($preset);
+    $self->current_preset($preset);
+    
+    # We reload presets in order to remove the "(modified)" suffix in case user was 
+    # prompted and chose to discard changes.
+    $self->load_presets;
+    
+    $preset->load_config if !$preset->_loaded;
+    $self->config->clear;
+    $self->config->apply($preset->dirty_config);
+    
     eval {
         local $SIG{__WARN__} = Slic3r::GUI::warning_catcher($self);
-        $self->{config}->clear;
-        $self->{config}->apply($preset_config);
         ($preset->default || $preset->external)
             ? $self->{btn_delete_preset}->Disable
             : $self->{btn_delete_preset}->Enable;
@@ -266,14 +221,6 @@ sub on_select_preset {
         $@ = "I was unable to load the selected config file: $@";
         Slic3r::GUI::catch_error($self);
     }
-        
-    # use CallAfter because some field triggers schedule on_change calls using CallAfter,
-    # and we don't want them to be called after this update_dirty() as they would mark the 
-    # preset dirty again
-    # (not sure this is true anymore now that update_dirty is idempotent)
-    wxTheApp->CallAfter(sub {
-        $self->update_dirty;
-    });
 }
 
 sub add_options_page {
@@ -323,89 +270,35 @@ sub update_tree {
     }
 }
 
-sub update_dirty {
-    my $self = shift;
-    
-    foreach my $i (0..$#{$self->{presets}}) {
-        my $preset = $self->get_preset($i);
-        if ($i == $self->current_preset && $self->is_dirty) {
-            $self->{presets_choice}->SetString($i, $preset->name . " (modified)");
-        } else {
-            $self->{presets_choice}->SetString($i, $preset->name);
-        }
-    }
-    $self->{presets_choice}->SetSelection($self->current_preset);  # http://trac.wxwidgets.org/ticket/13769
-}
-
-sub is_dirty {
-    my $self = shift;
-    return @{$self->dirty_options} > 0;
-}
-
-sub dirty_options {
-    my $self = shift;
-    
-    return [] if !defined $self->current_preset;  # happens during initialization
-    
-    my $preset_config = $self->get_current_preset_config;
-    return [
-        (grep !$preset_config->has($_), @{$self->{config}->get_keys}),
-        (grep !$self->{config}->has($_), @{$preset_config->get_keys}),
-        @{ $self->{config}->diff($self->get_current_preset_config) },
-    ];
-}
-
 sub load_presets {
     my $self = shift;
     
-    $self->{presets} = [ wxTheApp->presets($self->name, 1) ];
-    $self->current_preset(undef);
+    my $presets = wxTheApp->presets->{$self->name};
     $self->{presets_choice}->Clear;
-    $self->{presets_choice}->Append($_->name) for @{$self->{presets}};
-    $self->select_preset(0);
-}
-
-sub load_config_file {
-    my $self = shift;
-    my ($file) = @_;
-    
-    # look for the loaded config among the existing menu items
-    my $i = first { $self->{presets}[$_]{file} eq $file && $self->{presets}[$_]{external} } 1..$#{$self->{presets}};
-    if (!$i) {
-        my $preset_name = basename($file);  # keep the .ini suffix
-        push @{$self->{presets}}, Slic3r::GUI::Preset->new(
-            file        => $file,
-            name        => $preset_name,
-            external    => 1,
-        );
-        $self->{presets_choice}->Append($preset_name);
-        $i = $#{$self->{presets}};
+    foreach my $preset (@$presets) {
+        $self->{presets_choice}->Append($preset->dropdown_name);
+        
+        # Preserve selection.
+        if ($self->current_preset && $self->current_preset->name eq $preset->name) {
+            $self->{presets_choice}->SetSelection($self->{presets_choice}->GetCount-1);
+        }
     }
-    $self->{presets_choice}->SetSelection($i);
-    $self->on_select_preset;
 }
 
-sub load_config {
+# This is called internally whenever we make automatic adjustments to configuration
+# based on user actions.
+sub _load_config {
     my $self = shift;
     my ($config) = @_;
     
-    foreach my $opt_key (@{$self->{config}->diff($config)}) {
-        $self->{config}->set($opt_key, $config->get($opt_key));
-        $self->update_dirty;
-    }
+    my $diff = $self->config->diff($config);
+    $self->config->set($_, $config->get($_)) for @$diff;
+    # First apply all changes, then call all the _on_value_change triggers.
+    $self->_on_value_change($_) for @$diff;
     $self->reload_config;
     $self->_update;
 }
 
-sub get_preset_config {
-    my ($self, $preset) = @_;
-    
-    return $preset->config(
-        [ $self->options ],
-        [ $self->overriding_options ],
-    );
-}
-
 sub get_field {
     my ($self, $opt_key, $opt_index) = @_;
     
@@ -452,16 +345,15 @@ sub _compatible_printers_widget {
                 "Compatible printers", \@presets);
             
             my @selections = ();
-            foreach my $preset_name (@{ $self->{config}->get('compatible_printers') }) {
+            foreach my $preset_name (@{ $self->config->get('compatible_printers') }) {
                 push @selections, first { $presets[$_] eq $preset_name } 0..$#presets;
             }
             $dlg->SetSelections(@selections);
             
             if ($dlg->ShowModal == wxID_OK) {
                 my $value = [ @presets[$dlg->GetSelections] ];
-                $self->{config}->set('compatible_printers', $value);
-                $self->update_dirty;
-                $self->_on_value_change('compatible_printers', $value);
+                $self->config->set('compatible_printers', $value);
+                $self->_on_value_change('compatible_printers');
             }
         });
         
@@ -554,16 +446,15 @@ sub build {
                 [ map $options{$_}, @opt_keys ]);
             
             my @selections = ();
-            foreach my $opt_key (@{ $self->{config}->get('overridable') }) {
+            foreach my $opt_key (@{ $self->config->get('overridable') }) {
                 push @selections, first { $opt_keys[$_] eq $opt_key } 0..$#opt_keys;
             }
             $dlg->SetSelections(@selections);
             
             if ($dlg->ShowModal == wxID_OK) {
                 my $value = [ @opt_keys[$dlg->GetSelections] ];
-                $self->{config}->set('overridable', $value);
-                $self->update_dirty;
-                $self->_on_value_change('overridable', $value);
+                $self->config->set('overridable', $value);
+                $self->_on_value_change('overridable');
             }
         });
         
@@ -850,11 +741,11 @@ sub _update {
             $new_conf->set("top_solid_layers", 0);
             $new_conf->set("fill_density", 0);
             $new_conf->set("support_material", 0);
-            $self->load_config($new_conf);
+            $self->_load_config($new_conf);
         } else {
             my $new_conf = Slic3r::Config->new;
             $new_conf->set("spiral_vase", 0);
-            $self->load_config($new_conf);
+            $self->_load_config($new_conf);
         }
     }
 
@@ -880,7 +771,7 @@ sub _update {
                     $new_conf->set("support_material", 0);
                     $self->{support_material_overhangs_queried} = 0;
                 }
-                $self->load_config($new_conf);
+                $self->_load_config($new_conf);
             }
         }
     } else {
@@ -900,7 +791,7 @@ sub _update {
         } else {
             $new_conf->set("fill_density", 40);
         }
-        $self->load_config($new_conf);
+        $self->_load_config($new_conf);
     }
     
     my $have_perimeters = $config->perimeters > 0;
@@ -975,8 +866,6 @@ sub _update {
         for qw(standby_temperature_delta);
 }
 
-sub hidden_options { !$Slic3r::have_threads ? qw(threads) : () }
-
 package Slic3r::GUI::PresetEditor::Filament;
 use base 'Slic3r::GUI::PresetEditor';
 
@@ -1150,9 +1039,11 @@ sub build {
                     $self->{overrides_panel} = my $panel = Slic3r::GUI::Plater::OverrideSettingsPanel->new($parent,
                         size => [-1, 300],
                         on_change => sub {
-                            $self->{config}->erase($_) for @overridable;
-                            $self->{config}->apply($self->{overrides_config});
-                            $self->update_dirty;
+                            my ($opt_key) = @_;
+                            $self->config->erase($_) for @overridable;
+                            $self->current_preset->_dirty_config->erase($_) for @overridable;
+                            $self->config->apply($self->{overrides_config});
+                            $self->_on_value_change($opt_key);
                         });
                     $panel->set_editable(1);
                     $panel->set_default_config($self->{overrides_default_config});
@@ -1172,8 +1063,8 @@ sub reload_config {
     
     $self->{overrides_config}->clear;
     foreach my $opt_key (@{$self->{overrides_default_config}->get_keys}) {
-        if ($self->{config}->has($opt_key)) {
-            $self->{overrides_config}->set($opt_key, $self->{config}->get($opt_key));
+        if ($self->config->has($opt_key)) {
+            $self->{overrides_config}->set($opt_key, $self->config->get($opt_key));
         }
     }
     $self->{overrides_panel}->update_optgroup;
@@ -1186,10 +1077,10 @@ sub _update {
     
     $self->_update_description;
     
-    my $cooling = $self->{config}->cooling;
+    my $cooling = $self->config->cooling;
     $self->get_field($_)->toggle($cooling)
         for qw(max_fan_speed fan_below_layer_time slowdown_below_layer_time min_print_speed);
-    $self->get_field($_)->toggle($cooling || $self->{config}->fan_always_on)
+    $self->get_field($_)->toggle($cooling || $self->config->fan_always_on)
         for qw(min_fan_speed disable_fan_first_layers);
 }
 
@@ -1269,12 +1160,11 @@ sub build {
                 label => 'Bed shape',
             );
             $line->append_button("Set…", "cog.png", sub {
-                my $dlg = Slic3r::GUI::BedShapeDialog->new($self, $self->{config}->bed_shape);
+                my $dlg = Slic3r::GUI::BedShapeDialog->new($self, $self->config->bed_shape);
                 if ($dlg->ShowModal == wxID_OK) {
                     my $value = $dlg->GetValue;
-                    $self->{config}->set('bed_shape', $value);
-                    $self->update_dirty;
-                    $self->_on_value_change('bed_shape', $value);
+                    $self->config->set('bed_shape', $value);
+                    $self->_on_value_change('bed_shape');
                 }
             });
             $optgroup->append_line($line);
@@ -1301,7 +1191,6 @@ sub build {
                     wxTheApp->CallAfter(sub {
                         $self->_extruders_count_changed($optgroup->get_value('extruders_count'));
                     });
-                    $self->update_dirty;
                 }
             });
         }
@@ -1328,8 +1217,8 @@ sub build {
             $line->append_button("Test", "wrench.png", sub {
                 my $sender = Slic3r::GCode::Sender->new;
                 my $res = $sender->connect(
-                    $self->{config}->serial_port,
-                    $self->{config}->serial_speed,
+                    $self->config->serial_port,
+                    $self->config->serial_speed,
                 );
                 if ($res && $sender->wait_connected) {
                     Slic3r::GUI::show_info($self, "Connection to printer works correctly.", "Success!");
@@ -1355,10 +1244,8 @@ sub build {
                     my $dlg = Slic3r::GUI::BonjourBrowser->new($self, $entries);
                     if ($dlg->ShowModal == wxID_OK) {
                         my $value = $dlg->GetValue . ":" . $dlg->GetPort;
-                        $self->{config}->set('octoprint_host', $value);
-                        $self->update_dirty;
-                        $self->_on_value_change('octoprint_host', $value);
-                        $self->reload_config;
+                        $self->config->set('octoprint_host', $value);
+                        $self->_on_value_change('octoprint_host');
                     }
                 } else {
                     Wx::MessageDialog->new($self, 'No Bonjour device found', 'Device Browser', wxOK | wxICON_INFORMATION)->ShowModal;
@@ -1369,8 +1256,8 @@ sub build {
                 $ua->timeout(10);
 
                 my $res = $ua->get(
-                    "http://" . $self->{config}->octoprint_host . "/api/version",
-                    'X-Api-Key' => $self->{config}->octoprint_apikey,
+                    "http://" . $self->config->octoprint_host . "/api/version",
+                    'X-Api-Key' => $self->config->octoprint_apikey,
                 );
                 if ($res->is_success) {
                     Slic3r::GUI::show_info($self, "Connection to OctoPrint works correctly.", "Success!");
@@ -1462,7 +1349,7 @@ sub _extruders_count_changed {
     
     $self->{extruders_count} = $extruders_count;
     $self->_build_extruder_pages;
-    $self->_on_value_change('extruders_count', $extruders_count);
+    $self->_on_value_change('extruders_count');
     $self->_update;
 }
 
@@ -1477,7 +1364,7 @@ sub _build_extruder_pages {
     foreach my $extruder_idx (@{$self->{extruder_pages}} .. $self->{extruders_count}-1) {
         # extend options
         foreach my $opt_key ($self->_extruder_options) {
-            my $values = $self->{config}->get($opt_key);
+            my $values = $self->config->get($opt_key);
             if (!defined $values) {
                 $values = [ $default_config->get_at($opt_key, 0) ];
             } else {
@@ -1485,7 +1372,7 @@ sub _build_extruder_pages {
                 my $last_value = $values->[-1];
                 $values->[$extruder_idx] //= $last_value;
             }
-            $self->{config}->set($opt_key, $values)
+            $self->config->set($opt_key, $values)
                 or die "Unable to extend $opt_key";
         }
         
@@ -1531,9 +1418,9 @@ sub _build_extruder_pages {
     
     # remove extra config values
     foreach my $opt_key ($self->_extruder_options) {
-        my $values = $self->{config}->get($opt_key);
+        my $values = $self->config->get($opt_key);
         splice @$values, $self->{extruders_count} if $self->{extruders_count} <= $#$values;
-        $self->{config}->set($opt_key, $values)
+        $self->config->set($opt_key, $values)
             or die "Unable to truncate $opt_key";
     }
     
@@ -1610,7 +1497,7 @@ sub _update {
             } else {
                 $new_conf->set("use_firmware_retraction", 0);
             }
-            $self->load_config($new_conf);
+            $self->_load_config($new_conf);
         }
         
         $self->get_field('retract_length_toolchange', $i)->toggle($have_multiple_extruders);
@@ -1628,7 +1515,7 @@ sub on_preset_loaded {
     # update the extruders count field
     {
         # update the GUI field according to the number of nozzle diameters supplied
-        my $extruders_count = scalar @{ $self->{config}->nozzle_diameter };
+        my $extruders_count = scalar @{ $self->config->nozzle_diameter };
         $self->set_value('extruders_count', $extruders_count);
         $self->_extruders_count_changed($extruders_count);
     }
@@ -1642,7 +1529,7 @@ sub load_config_file {
         "Your configuration was imported. However, Slic3r is currently only able to import settings "
         . "for the first defined filament. We recommend you don't use exported configuration files "
         . "for multi-extruder setups and rely on the built-in preset management system instead.")
-        if @{ $self->{config}->nozzle_diameter } > 1;
+        if @{ $self->config->nozzle_diameter } > 1;
 }
 
 package Slic3r::GUI::PresetEditor::Page;
@@ -1676,8 +1563,7 @@ sub new_optgroup {
         on_change       => sub {
             my ($opt_key, $value) = @_;
             wxTheApp->CallAfter(sub {
-                $self->GetParent->update_dirty;
-                $self->GetParent->_on_value_change($opt_key, $value);
+                $self->GetParent->_on_value_change($opt_key);
             });
         },
     );
@@ -1726,7 +1612,7 @@ sub new {
     
     my @values = @{$params{values}};
     
-    my $text = Wx::StaticText->new($self, -1, "Save " . lc($params{title}) . " as:", wxDefaultPosition, wxDefaultSize);
+    my $text = Wx::StaticText->new($self, -1, "Save profile as:", wxDefaultPosition, wxDefaultSize);
     $self->{combo} = Wx::ComboBox->new($self, -1, $params{default}, wxDefaultPosition, wxDefaultSize, \@values,
                                        wxTE_PROCESS_ENTER);
     my $buttons = $self->CreateStdDialogButtonSizer(wxOK | wxCANCEL);
diff --git a/lib/Slic3r/GUI/PresetEditorDialog.pm b/lib/Slic3r/GUI/PresetEditorDialog.pm
index d706622a3..6385844c5 100644
--- a/lib/Slic3r/GUI/PresetEditorDialog.pm
+++ b/lib/Slic3r/GUI/PresetEditorDialog.pm
@@ -1,8 +1,8 @@
 package Slic3r::GUI::PresetEditorDialog;
 use strict;
 use warnings;
-use Wx qw(:dialog :id :misc :sizer :button :icon wxTheApp);
-use Wx::Event qw(EVT_CLOSE);
+use Wx qw(:dialog :id :misc :sizer :button :icon wxTheApp WXK_ESCAPE);
+use Wx::Event qw(EVT_CLOSE EVT_CHAR_HOOK);
 use base qw(Wx::Dialog Class::Accessor);
 use utf8;
 
@@ -15,7 +15,6 @@ sub new {
     
     $self->preset_editor($self->preset_editor_class->new($self));
     $self->SetTitle($self->preset_editor->title);
-    $self->preset_editor->load_presets;
     
     my $sizer = Wx::BoxSizer->new(wxVERTICAL);
     $sizer->Add($self->preset_editor, 1, wxEXPAND);
@@ -24,23 +23,32 @@ sub new {
     #$sizer->SetSizeHints($self);
     
     if (0) {
-        # This does not call the EVT_CLOSE below
         my $buttons = $self->CreateStdDialogButtonSizer(wxCLOSE);
         $sizer->Add($buttons, 0, wxEXPAND | wxBOTTOM | wxLEFT | wxRIGHT, 10);
     }
     
+    wxTheApp->restore_window_pos($self, "preset_editor");
+    
     EVT_CLOSE($self, sub {
         my (undef, $event) = @_;
         
-        if ($event->CanVeto && !$self->preset_editor->prompt_unsaved_changes) {
-            $event->Veto;
-            return;
-        }
+        # save window size
+        wxTheApp->save_window_pos($self, "preset_editor");
         
         # propagate event
         $event->Skip;
     });
     
+    EVT_CHAR_HOOK($self, sub {
+        my (undef, $event) = @_;
+        
+        if ($event->GetKeyCode == WXK_ESCAPE) {
+            $self->Close;
+        } else {
+            $event->Skip;
+        }
+    });
+    
     return $self;
 }
 
diff --git a/xs/src/libslic3r/Config.cpp b/xs/src/libslic3r/Config.cpp
index b5565ea76..f18e4e025 100644
--- a/xs/src/libslic3r/Config.cpp
+++ b/xs/src/libslic3r/Config.cpp
@@ -532,6 +532,11 @@ DynamicConfig::clear() {
     this->options.clear();
 }
 
+bool
+DynamicConfig::empty() const {
+    return this->options.empty();
+}
+
 void
 DynamicConfig::read_cli(const std::vector<std::string> &tokens, t_config_option_keys* extra)
 {
diff --git a/xs/src/libslic3r/Config.hpp b/xs/src/libslic3r/Config.hpp
index 45ba8a3ba..41d3cc668 100644
--- a/xs/src/libslic3r/Config.hpp
+++ b/xs/src/libslic3r/Config.hpp
@@ -678,6 +678,7 @@ class DynamicConfig : public virtual ConfigBase
     t_config_option_keys keys() const;
     void erase(const t_config_option_key &opt_key);
     void clear();
+    bool empty() const;
     void read_cli(const std::vector<std::string> &tokens, t_config_option_keys* extra);
     void read_cli(const int argc, const char **argv, t_config_option_keys* extra);
     
diff --git a/xs/xsp/Config.xsp b/xs/xsp/Config.xsp
index 25da96477..6744a1e10 100644
--- a/xs/xsp/Config.xsp
+++ b/xs/xsp/Config.xsp
@@ -40,6 +40,7 @@
     %name{get_keys} std::vector<std::string> keys();
     void erase(t_config_option_key opt_key);
     void clear();
+    bool empty();
     void normalize();
     %name{setenv} void setenv_();
     double min_object_distance();