Fix for #8439 - Inches units and scaling not working.

It changes values if clicked into boxes multiple times!

src/slic3r/GUI/GUI_ObjectManipulation.hpp

@@ -85,6 +85,7 @@ private:
         Vec3d scale;
         Vec3d scale_rounded;
         Vec3d size;
+        Vec3d size_inches;
         Vec3d size_rounded;
 
         wxString move_label_string;