Fixed OSX build and a bug when for part is able to add "layer_height" option

src/slic3r/GUI/GUI_ObjectLayers.hpp

@@ -4,18 +4,22 @@
 #include "GUI_ObjectSettings.hpp"
 #include "wxExtensions.hpp"
 
+#ifdef __WXOSX__
+#include "..\libslic3r\PrintConfig.hpp"
+#endif
+
 class wxBoxSizer;
 
 namespace Slic3r {
 class ModelObject;
 
+namespace GUI {
+class ConfigOptionsGroup;
+
 typedef double                                              coordf_t;
 typedef std::pair<coordf_t, coordf_t>                       t_layer_height_range;
 typedef std::map<t_layer_height_range, DynamicPrintConfig>  t_layer_config_ranges;
 
-namespace GUI {
-class ConfigOptionsGroup;
-
 class LayerRangeEditor : public wxTextCtrl
 {
     bool                m_enter_pressed     { false };