diff --git a/lib/Slic3r/GUI/Plater.pm b/lib/Slic3r/GUI/Plater.pm
index 352fe25ea3..46e2d3e090 100644
--- a/lib/Slic3r/GUI/Plater.pm
+++ b/lib/Slic3r/GUI/Plater.pm
@@ -26,6 +26,7 @@ my $MESSAGE_DIALOG_EVENT    : shared = Wx::NewEventType;
 my $EXPORT_COMPLETED_EVENT  : shared = Wx::NewEventType;
 my $EXPORT_FAILED_EVENT     : shared = Wx::NewEventType;
 
+use constant CANVAS_SIZE => [300,300];
 use constant CANVAS_TEXT => join('-', +(localtime)[3,4]) eq '13-8'
     ? 'What do you want to print today? ™' # Sept. 13, 2006. The first part ever printed by a RepRap to make another RepRap.
     : 'Drag your objects here';
@@ -38,7 +39,7 @@ sub new {
         bed_size print_center complete_objects extruder_clearance_radius skirts skirt_distance
     ));
     
-    $self->{canvas} = Wx::Panel->new($self, -1, wxDefaultPosition, [300, 300], wxTAB_TRAVERSAL);
+    $self->{canvas} = Wx::Panel->new($self, -1, wxDefaultPosition, CANVAS_SIZE, wxTAB_TRAVERSAL);
     $self->{canvas}->SetBackgroundColour(Wx::wxWHITE);
     EVT_PAINT($self->{canvas}, \&repaint);
     EVT_MOUSE_EVENTS($self->{canvas}, \&mouse_event);
@@ -679,8 +680,10 @@ sub recenter {
 sub on_config_change {
     my $self = shift;
     my ($opt_key, $value) = @_;
-    $self->{config}->set($opt_key, $value) if exists $self->{config}{$opt_key};
-    $self->_update_bed_size;
+    if (exists $self->{config}{$opt_key}) {
+        $self->{config}->set($opt_key, $value);
+        $self->_update_bed_size if $opt_key eq 'bed_size';
+    }
 }
 
 sub _update_bed_size {
@@ -689,7 +692,7 @@ sub _update_bed_size {
     # supposing the preview canvas is square, calculate the scaling factor
     # to constrain print bed area inside preview
     my $bed_size = $self->{config}->bed_size;
-    my $canvas_side = $self->{canvas}->GetSize->GetWidth;
+    my $canvas_side = CANVAS_SIZE->[X];  # when the canvas is not rendered yet, its GetSize() method returns 0,0
     my $bed_largest_side = $bed_size->[X] > $bed_size->[Y] ? $bed_size->[X] : $bed_size->[Y];
     my $old_scaling_factor = $self->{scaling_factor};
     $self->{scaling_factor} = $canvas_side / $bed_largest_side;
diff --git a/lib/Slic3r/GUI/SkeinPanel.pm b/lib/Slic3r/GUI/SkeinPanel.pm
index f0446f8fe6..be81a0a455 100644
--- a/lib/Slic3r/GUI/SkeinPanel.pm
+++ b/lib/Slic3r/GUI/SkeinPanel.pm
@@ -20,18 +20,16 @@ sub new {
     
     $self->{tabpanel} = Wx::Notebook->new($self, -1, wxDefaultPosition, wxDefaultSize, wxNB_TOP | wxTAB_TRAVERSAL);
     $self->{tabpanel}->AddPage($self->{plater} = Slic3r::GUI::Plater->new($self->{tabpanel}), "Plater");
-    $self->{options_tabs} = {
-        print       => Slic3r::GUI::Tab::Print->new     ($self->{tabpanel}, sync_presets_with => $self->{plater}{preset_choosers}{print}),
-        filament    => Slic3r::GUI::Tab::Filament->new  ($self->{tabpanel}, sync_presets_with => $self->{plater}{preset_choosers}{filament}),
-        printer     => Slic3r::GUI::Tab::Printer->new   ($self->{tabpanel}, sync_presets_with => $self->{plater}{preset_choosers}{printer}),
-    };
+    $self->{options_tabs} = {};
     
-    # propagate config change events to the plater
-    $_->{on_value_change} = sub { $self->{plater}->on_config_change(@_) } for values %{$self->{options_tabs}};
-    
-    $self->{tabpanel}->AddPage($self->{options_tabs}{print}, $self->{options_tabs}{print}->title);
-    $self->{tabpanel}->AddPage($self->{options_tabs}{filament}, $self->{options_tabs}{filament}->title);
-    $self->{tabpanel}->AddPage($self->{options_tabs}{printer}, $self->{options_tabs}{printer}->title);
+    for my $tab_name (qw(print filament printer)) {
+        $self->{options_tabs}{$tab_name} = ("Slic3r::GUI::Tab::" . ucfirst $tab_name)->new(
+            $self->{tabpanel},
+            sync_presets_with   => $self->{plater}{preset_choosers}{$tab_name},
+            on_value_change     => sub { $self->{plater}->on_config_change(@_) }, # propagate config change events to the plater
+        );
+        $self->{tabpanel}->AddPage($self->{options_tabs}{$tab_name}, $self->{options_tabs}{$tab_name}->title);
+    }
     
     my $sizer = Wx::BoxSizer->new(wxVERTICAL);
     $sizer->Add($self->{tabpanel}, 1, wxEXPAND);
diff --git a/lib/Slic3r/GUI/Tab.pm b/lib/Slic3r/GUI/Tab.pm
index 4fb07a5b44..284dea1752 100644
--- a/lib/Slic3r/GUI/Tab.pm
+++ b/lib/Slic3r/GUI/Tab.pm
@@ -15,7 +15,7 @@ sub new {
     my $self = $class->SUPER::new($parent, -1, wxDefaultPosition, wxDefaultSize, wxBK_LEFT | wxTAB_TRAVERSAL);
     $self->{options} = []; # array of option names handled by this tab
     
-    $self->{sync_presets_with} = $params{sync_presets_with};
+    $self->{$_} = $params{$_} for qw(sync_presets_with on_value_change);
     EVT_CHOICE($parent, $self->{sync_presets_with}, sub {
         $self->{presets_choice}->SetSelection($self->{sync_presets_with}->GetSelection);
         $self->on_select_preset;