From c3eaeae45cd6d63633a93d39228c12b4d2a8a31b Mon Sep 17 00:00:00 2001
From: Marius Kintel <marius@kintel.net>
Date: Tue, 31 Dec 2013 02:53:04 -0500
Subject: [PATCH] bugfix: forgot to negate statement when refactoring

---
 src/mainwin.cc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/mainwin.cc b/src/mainwin.cc
index a5a6d2c5..cc46ced2 100644
--- a/src/mainwin.cc
+++ b/src/mainwin.cc
@@ -1438,7 +1438,7 @@ void MainWindow::actionExportSTLorOFF(bool)
 	}
 
 	const CGAL_Nef_polyhedron *N = dynamic_cast<const CGAL_Nef_polyhedron *>(this->root_geom.get());
-	if (N && N->p3->is_simple()) {
+	if (N && !N->p3->is_simple()) {
 		PRINT("Object isn't a valid 2-manifold! Modify your design. See http://en.wikibooks.org/wiki/OpenSCAD_User_Manual/STL_Import_and_Export");
 		clearCurrentOutput();
 		return;