diff --git a/Arrangement_on_surface_2/demo/Arrangement_on_surface_2/CMakeLists.txt b/Arrangement_on_surface_2/demo/Arrangement_on_surface_2/CMakeLists.txt
index 2666cdd1ad9..01f446b7308 100644
--- a/Arrangement_on_surface_2/demo/Arrangement_on_surface_2/CMakeLists.txt
+++ b/Arrangement_on_surface_2/demo/Arrangement_on_surface_2/CMakeLists.txt
@@ -10,8 +10,8 @@ endif()
 
 # set default build type
 if (NOT CMAKE_BUILD_TYPE)
-	set (CMAKE_BUILD_TYPE "Debug" CACHE STRING
-		"Choose the type of build, options are: Debug Release" FORCE)
+    set (CMAKE_BUILD_TYPE "Debug" CACHE STRING
+        "Choose the type of build, options are: Debug Release" FORCE)
 endif()
 
 find_package(CGAL COMPONENTS Core Qt5)
@@ -23,70 +23,70 @@ find_package(Qt5 QUIET COMPONENTS Gui Widgets)
 add_definitions(-DQT_NO_KEYWORDS)
 
 if ( CGAL_FOUND AND CGAL_Qt5_FOUND AND Qt5_FOUND AND CGAL_Core_FOUND)
-	include_directories( ./ )
-	# Arrangement package includes
-	include_directories(BEFORE ../../include)
+    include_directories( ./ )
+    # Arrangement package includes
+    include_directories(BEFORE ../../include)
 
 
-	qt5_wrap_ui(arrangement_2_uis
-			  ArrangementDemoWindow.ui
-			  NewTabDialog.ui
-			  OverlayDialog.ui
-			  ArrangementDemoPropertiesDialog.ui
-			  AlgebraicCurveInputDialog.ui)
+    qt5_wrap_ui(arrangement_2_uis
+              ArrangementDemoWindow.ui
+              NewTabDialog.ui
+              OverlayDialog.ui
+              ArrangementDemoPropertiesDialog.ui
+              AlgebraicCurveInputDialog.ui)
 
-	qt5_wrap_cpp(CGAL_Qt5_MOC_FILES
-			   ArrangementDemoWindow.h
-			   ArrangementDemoTab.h
-			   GraphicsViewCurveInput.h
-			   Callback.h
-			   OverlayDialog.h
-			   ArrangementDemoPropertiesDialog.h
-			   AlgebraicCurveInputDialog.h
-			   ColorItemEditor.h
-			   DeleteCurveModeItemEditor.h
-			   PropertyValueDelegate.h)
+    qt5_wrap_cpp(CGAL_Qt5_MOC_FILES
+               ArrangementDemoWindow.h
+               ArrangementDemoTab.h
+               GraphicsViewCurveInput.h
+               Callback.h
+               OverlayDialog.h
+               ArrangementDemoPropertiesDialog.h
+               AlgebraicCurveInputDialog.h
+               ColorItemEditor.h
+               DeleteCurveModeItemEditor.h
+               PropertyValueDelegate.h)
 
-	qt5_add_resources(CGAL_Qt5_RESOURCE_FILES ArrangementDemoWindow.qrc)
+    qt5_add_resources(CGAL_Qt5_RESOURCE_FILES ArrangementDemoWindow.qrc)
 
-	add_executable(arrangement_2
-				 arrangement_2.cpp
-				 ArrangementDemoWindow.cpp
-				 ArrangementDemoTab.cpp
-				 ArrangementDemoGraphicsView.cpp
-				 ArrangementGraphicsItem.cpp
-				 Callback.cpp
-				 VerticalRayShootCallback.cpp
-				 EnvelopeCallback.cpp
-				 SplitEdgeCallback.cpp
-				 FillFaceCallback.cpp
-				 GraphicsViewSegmentInput.cpp
-				 Utils.cpp
-				 NewTabDialog.cpp
-				 OverlayDialog.cpp
-				 ArrangementDemoPropertiesDialog.cpp
-				 AlgebraicCurveInputDialog.cpp
-				 ColorItemEditor.cpp
-				 PropertyValueDelegate.cpp
-				 DeleteCurveMode.cpp
-				 DeleteCurveModeItemEditor.cpp
-				 PointsGraphicsItem.cpp
-				 VerticalRayGraphicsItem.cpp
-				 DeleteCurveCallback.cpp
-				 CurveGraphicsItem.cpp
-				 ArrangementPainterOstream.cpp
-				 GraphicsViewCurveInput.cpp
-				 AlgebraicCurveParser.cpp
-				 ${CGAL_Qt5_MOC_FILES}
-				 ${arrangement_2_uis}
-				 ${CGAL_Qt5_RESOURCE_FILES})
+    add_executable(arrangement_2
+                 arrangement_2.cpp
+                 ArrangementDemoWindow.cpp
+                 ArrangementDemoTab.cpp
+                 ArrangementDemoGraphicsView.cpp
+                 ArrangementGraphicsItem.cpp
+                 Callback.cpp
+                 VerticalRayShootCallback.cpp
+                 EnvelopeCallback.cpp
+                 SplitEdgeCallback.cpp
+                 FillFaceCallback.cpp
+                 GraphicsViewSegmentInput.cpp
+                 Utils.cpp
+                 NewTabDialog.cpp
+                 OverlayDialog.cpp
+                 ArrangementDemoPropertiesDialog.cpp
+                 AlgebraicCurveInputDialog.cpp
+                 ColorItemEditor.cpp
+                 PropertyValueDelegate.cpp
+                 DeleteCurveMode.cpp
+                 DeleteCurveModeItemEditor.cpp
+                 PointsGraphicsItem.cpp
+                 VerticalRayGraphicsItem.cpp
+                 DeleteCurveCallback.cpp
+                 CurveGraphicsItem.cpp
+                 ArrangementPainterOstream.cpp
+                 GraphicsViewCurveInput.cpp
+                 AlgebraicCurveParser.cpp
+                 ${CGAL_Qt5_MOC_FILES}
+                 ${arrangement_2_uis}
+                 ${CGAL_Qt5_RESOURCE_FILES})
 
-	qt5_use_modules(arrangement_2 Core Gui Widgets Script)
-	target_link_libraries(arrangement_2 CGAL::CGAL CGAL::CGAL_Qt5 CGAL::CGAL_Core)
-	add_to_cached_list(CGAL_EXECUTABLE_TARGETS arrangement_2)
+    qt5_use_modules(arrangement_2 Core Gui Widgets Script)
+    target_link_libraries(arrangement_2 CGAL::CGAL CGAL::CGAL_Qt5 CGAL::CGAL_Core)
+    add_to_cached_list(CGAL_EXECUTABLE_TARGETS arrangement_2)
 
-	include(${CGAL_MODULES_DIR}/CGAL_add_test.cmake)
-	cgal_add_compilation_test(arrangement_2)
+    include(${CGAL_MODULES_DIR}/CGAL_add_test.cmake)
+    cgal_add_compilation_test(arrangement_2)
 else()
   message(STATUS "NOTICE: This demo requires CGAL, CGAL-Core and Qt5, and will not be compiled.")
 endif()