Includes cleanup:

GUI_App.hpp      (should not include) MainFrame.hpp
MainFrame.hpp    Plater.hpp
ModelArrange.hpp Model.hpp
Slicing.hpp      PrintConfig.hpp
FillBase.hpp     PrintConfig.hpp
GUI_App.hpp      PrintConfig.hpp
OptionsGroup.hpp GUI_App.hpp

src/slic3r/GUI/Gizmos/GLGizmoCut.cpp

@@ -12,6 +12,7 @@
 #include <algorithm>
 
 #include "slic3r/GUI/GUI_App.hpp"
+#include "slic3r/GUI/Plater.hpp"
 
 
 namespace Slic3r {

src/slic3r/GUI/Gizmos/GLGizmoFdmSupports.cpp

@@ -8,6 +8,7 @@
 #include "slic3r/GUI/GUI_App.hpp"
 #include "slic3r/GUI/PresetBundle.hpp"
 #include "slic3r/GUI/Camera.hpp"
+#include "slic3r/GUI/Plater.hpp"
 #include "libslic3r/Model.hpp"
 
 

src/slic3r/GUI/Gizmos/GLGizmoSlaSupports.cpp

@@ -3,6 +3,7 @@
 #include "slic3r/GUI/GLCanvas3D.hpp"
 #include "slic3r/GUI/Camera.hpp"
 #include "slic3r/GUI/Gizmos/GLGizmosCommon.hpp"
+#include "slic3r/GUI/MainFrame.hpp"
 
 #include <GL/glew.h>
 

src/slic3r/GUI/Gizmos/GLGizmosCommon.cpp

@@ -6,6 +6,7 @@
 #include "libslic3r/SLAPrint.hpp"
 #include "slic3r/GUI/GUI_App.hpp"
 #include "slic3r/GUI/Camera.hpp"
+#include "slic3r/GUI/Plater.hpp"
 
 #include <GL/glew.h>
 

src/slic3r/GUI/Gizmos/GLGizmosManager.cpp

@@ -6,6 +6,7 @@
 #include "slic3r/GUI/GUI_App.hpp"
 #include "slic3r/GUI/GUI_ObjectManipulation.hpp"
 #include "slic3r/GUI/PresetBundle.hpp"
+#include "slic3r/GUI/Plater.hpp"
 #include "slic3r/Utils/UndoRedo.hpp"
 
 #include "slic3r/GUI/Gizmos/GLGizmoMove.hpp"