diff --git a/lib/Slic3r/GUI/MainFrame.pm b/lib/Slic3r/GUI/MainFrame.pm
index 1f27a9724..ad2eca91d 100644
--- a/lib/Slic3r/GUI/MainFrame.pm
+++ b/lib/Slic3r/GUI/MainFrame.pm
@@ -326,6 +326,7 @@ sub is_loaded {
     return $self->{loaded};
 }
 
+# Selection of a 3D object changed on the platter.
 sub on_plater_selection_changed {
     my ($self, $have_selection) = @_;
     
@@ -523,10 +524,9 @@ sub export_config {
     $dlg->Destroy;
 }
 
+# Load a config file containing a Print, Filament & Printer preset.
 sub load_config_file {
-    my $self = shift;
-    my ($file) = @_;
-    
+    my ($self, $file) = @_;
     if (!$file) {
         return unless $self->check_unsaved_changes;
         my $dir = $last_config ? dirname($last_config) : $Slic3r::GUI::Settings->{recent}{config_directory} || $Slic3r::GUI::Settings->{recent}{skein_directory} || '';
@@ -638,6 +638,8 @@ sub load_configbundle {
     Slic3r::GUI::show_info($self, $message);
 }
 
+# Load a provied DynamicConfig into the Print / Filament / Printer tabs, thus modifying the active preset.
+# Also update the platter with the new presets.
 sub load_config {
     my $self = shift;
     my ($config) = @_;
diff --git a/lib/Slic3r/GUI/Plater/ObjectPartsPanel.pm b/lib/Slic3r/GUI/Plater/ObjectPartsPanel.pm
index a8628a634..707929e33 100644
--- a/lib/Slic3r/GUI/Plater/ObjectPartsPanel.pm
+++ b/lib/Slic3r/GUI/Plater/ObjectPartsPanel.pm
@@ -17,8 +17,7 @@ use constant ICON_SOLIDMESH     => 1;
 use constant ICON_MODIFIERMESH  => 2;
 
 sub new {
-    my $class = shift;
-    my ($parent, %params) = @_;
+    my ($class, $parent, %params) = @_;
     my $self = $class->SUPER::new($parent, -1, wxDefaultPosition, wxDefaultSize, wxTAB_TRAVERSAL);
     
     # C++ type Slic3r::ModelObject
diff --git a/lib/Slic3r/GUI/Plater/ObjectSettingsDialog.pm b/lib/Slic3r/GUI/Plater/ObjectSettingsDialog.pm
index 971d688cb..908d5eff7 100644
--- a/lib/Slic3r/GUI/Plater/ObjectSettingsDialog.pm
+++ b/lib/Slic3r/GUI/Plater/ObjectSettingsDialog.pm
@@ -15,8 +15,7 @@ use base 'Wx::Dialog';
 # %params{object} of a Perl type Slic3r::GUI::Plater::Object
 # %params{model_object} of a C++ type Slic3r::ModelObject
 sub new {
-    my $class = shift;
-    my ($parent, %params) = @_;
+    my ($class, $parent, %params) = @_;
     my $self = $class->SUPER::new($parent, -1, "Settings for " . $params{object}->name, wxDefaultPosition, [700,500], wxDEFAULT_DIALOG_STYLE | wxRESIZE_BORDER);
     $self->{$_} = $params{$_} for keys %params;
 
diff --git a/lib/Slic3r/GUI/Plater/OverrideSettingsPanel.pm b/lib/Slic3r/GUI/Plater/OverrideSettingsPanel.pm
index d99b470db..2f8b8ce73 100644
--- a/lib/Slic3r/GUI/Plater/OverrideSettingsPanel.pm
+++ b/lib/Slic3r/GUI/Plater/OverrideSettingsPanel.pm
@@ -29,8 +29,7 @@ my %icons = (
 );
 
 sub new {
-    my $class = shift;
-    my ($parent, %params) = @_;
+    my ($class, $parent, %params) = @_;
     my $self = $class->SUPER::new($parent, -1, wxDefaultPosition, wxDefaultSize, wxTAB_TRAVERSAL);
     # C++ class Slic3r::DynamicPrintConfig, initially empty.
     $self->{default_config} = Slic3r::Config->new;
diff --git a/lib/Slic3r/GUI/Tab.pm b/lib/Slic3r/GUI/Tab.pm
index c2de563e2..db1521499 100644
--- a/lib/Slic3r/GUI/Tab.pm
+++ b/lib/Slic3r/GUI/Tab.pm
@@ -384,9 +384,10 @@ sub update_tree {
     }
 }
 
+# Update the combo box label of the selected preset based on its "dirty" state,
+# comparing the selected preset config with $self->{config}.
 sub update_dirty {
-    my $self = shift;
-    
+    my ($self) = @_;
     my $list_updated;
     foreach my $i ($self->{default_suppressed}..$#{$self->{presets}}) {
         my $preset = $self->get_preset($i);
@@ -401,20 +402,23 @@ sub update_dirty {
     $self->_on_presets_changed;
 }
 
+# Has the selected preset been modified?
 sub is_dirty {
-    my $self = shift;
+    my ($self) = @_;
     return @{$self->dirty_options} > 0;
 }
 
+# Which options of the selected preset were modified?
 sub dirty_options {
-    my $self = shift;
-    
+    my ($self) = @_;
     return [] if !defined $self->current_preset;  # happens during initialization
     return $self->get_preset_config($self->get_current_preset)->diff($self->{config});
 }
 
+# Search all ini files in the presets directory, add them into the list of $self->{presets} in the form of Slic3r::GUI::Tab::Preset.
+# Initialize the drop down list box.
 sub load_presets {
-    my $self = shift;
+    my ($self) = @_;
     
     $self->{presets} = [
         Slic3r::GUI::Tab::Preset->new(
@@ -445,10 +449,9 @@ sub load_presets {
     $self->_on_presets_changed;
 }
 
+# Load a config file containing a Print, Filament & Printer preset.
 sub load_config_file {
-    my $self = shift;
-    my ($file) = @_;
-    
+    my ($self, $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) {
@@ -470,9 +473,10 @@ sub load_config_file {
     return 1;
 }
 
+# Load a provied DynamicConfig into the tab, modifying the active preset.
+# This could be used for example by setting a Wipe Tower position by interactive manipulation in the 3D view.
 sub load_config {
-    my $self = shift;
-    my ($config) = @_;
+    my ($self, $config) = @_;
     
     my %keys_modified = ();
     foreach my $opt_key (@{$self->{config}->diff($config)}) {
@@ -487,6 +491,7 @@ sub load_config {
     }
 }
 
+# Load and return a config from the file associated with the $preset (Perl type Slic3r::GUI::Tab::Preset).
 sub get_preset_config {
     my ($self, $preset) = @_;
     return $preset->config($self->{config}->get_keys);
@@ -1705,6 +1710,7 @@ sub on_preset_loaded {
     }
 }
 
+# Load a config file containing a Print, Filament & Printer preset.
 sub load_config_file {
     my $self = shift;
     if ($self->SUPER::load_config_file(@_)) {
@@ -1847,6 +1853,8 @@ has 'external'  => (is => 'ro', default => sub { 0 });
 has 'name'      => (is => 'rw', required => 1);
 has 'file'      => (is => 'rw');
 
+# Load a config file, return a C++ class Slic3r::DynamicPrintConfig with $keys initialized from the config file.
+# In case of a "default" config item, return the default values.
 sub config {
     my ($self, $keys) = @_;
     
diff --git a/xs/src/libslic3r/PerimeterGenerator.cpp b/xs/src/libslic3r/PerimeterGenerator.cpp
index e5e4c5d60..bffd46d0f 100644
--- a/xs/src/libslic3r/PerimeterGenerator.cpp
+++ b/xs/src/libslic3r/PerimeterGenerator.cpp
@@ -511,11 +511,10 @@ PerimeterGenerator::_variable_width(const ThickPolylines &polylines, ExtrusionRo
         
         // append paths to collection
         if (!paths.empty()) {
-            if (paths.front().first_point().coincides_with(paths.back().last_point())) {
+            if (paths.front().first_point().coincides_with(paths.back().last_point()))
                 coll.append(ExtrusionLoop(paths));
-            } else {
+            else
                 coll.append(paths);
-            }
         }
     }