Ignore cut result if user didn't click the cut button

lib/Slic3r/GUI/Plater.pm

@@ -1541,7 +1541,7 @@ sub object_cut_dialog {
 		object              => $self->{objects}[$obj_idx],
 		model_object        => $self->{model}->objects->[$obj_idx],
 	);
-	$dlg->ShowModal;
+	return unless $dlg->ShowModal == wxID_OK;
 	
 	if (my @new_objects = $dlg->NewModelObjects) {
 	    $self->remove($obj_idx);

lib/Slic3r/GUI/Plater/ObjectCutDialog.pm

@@ -111,14 +111,9 @@ sub new {
     $self->SetMinSize($self->GetSize);
     $self->{sizer}->SetSizeHints($self);
     
-    # needed to actually free memory
-    EVT_CLOSE($self, sub {
-        $self->EndModal(wxID_OK);
-        $self->Destroy;
-    });
-    
     EVT_BUTTON($self, $self->{btn_cut}, sub {
         $self->perform_cut(1);
+        $self->EndModal(wxID_OK);
         $self->Close;
     });