diff --git a/src/GUI/GUI.hpp b/src/GUI/GUI.hpp
index c693e847b..e6c89b90f 100644
--- a/src/GUI/GUI.hpp
+++ b/src/GUI/GUI.hpp
@@ -2,14 +2,17 @@
 #define GUI_HPP
 #include "MainFrame.hpp"
 #include "Notifier.hpp"
+#include <string>
 
 namespace Slic3r { namespace GUI {
 
+// Friendly indices for the preset lists.
 enum class PresetID {
     PRINT = 0,
     FILAMENT = 1,
     PRINTER = 2
 };
+using preset_list = std::vector<std::string>;
 
 class App: public wxApp
 {
@@ -22,7 +25,7 @@ public:
 private:
     std::shared_ptr<Settings> gui_config; // GUI-specific configuration options
     Notifier* notifier;
-    
+    std::vector<preset_list> presets { preset_list(), preset_list(), preset_list() };
 };
 
 }} // namespace Slic3r::GUI
diff --git a/src/GUI/MainFrame.cpp b/src/GUI/MainFrame.cpp
index 547c0757b..f006423b1 100644
--- a/src/GUI/MainFrame.cpp
+++ b/src/GUI/MainFrame.cpp
@@ -15,6 +15,11 @@ MainFrame::MainFrame(const wxString& title, const wxPoint& pos, const wxSize& si
         tabpanel(nullptr), controller(nullptr), plater(nullptr), gui_config(config), preset_editor_tabs(std::map<wxWindowID, PresetEditor*>())
 {
     // Set icon to either the .ico if windows or png for everything else.
+    if (the_os == OS::Windows) 
+        this->SetIcon(wxIcon(var("Slic3r.ico"), wxBITMAP_TYPE_ICO));
+    else
+        this->SetIcon(wxIcon(var("Slic3r_128px.png"), wxBITMAP_TYPE_PNG));        
+    
 
     this->init_tabpanel();
     this->init_menubar();
diff --git a/src/GUI/misc_ui.cpp b/src/GUI/misc_ui.cpp
index b509cf097..278f6e4d7 100644
--- a/src/GUI/misc_ui.cpp
+++ b/src/GUI/misc_ui.cpp
@@ -11,5 +11,20 @@ void check_version(bool manual)  {
 
 #endif
 
+const wxString var(const wxString& in) {
+    wxFileName f(wxStandardPaths::Get().GetExecutablePath());
+    wxString appPath(f.GetPath());
+
+    // replace center string with path to VAR in actual distribution later
+    return appPath + "/../var/" + in;
+}
+
+/// Returns the path to Slic3r's default user data directory.
+const wxString home(const wxString& in) { 
+    if (the_os == OS::Windows) 
+        return wxGetHomeDir() + "/" + in + "/";
+    return wxGetHomeDir() + "/." + in + "/";
+}
+
 }} // namespace Slic3r::GUI
 
diff --git a/src/GUI/misc_ui.hpp b/src/GUI/misc_ui.hpp
index 83ef2646c..cc92e5a03 100644
--- a/src/GUI/misc_ui.hpp
+++ b/src/GUI/misc_ui.hpp
@@ -1,15 +1,44 @@
 #ifndef MISC_UI_HPP
 #define MISC_UI_HPP
 
+#include <wx/wxprec.h>
+#ifndef WX_PRECOMP
+    #include <wx/wx.h>
+#endif
+
+#include <wx/filename.h>
+#include <wx/stdpaths.h>
+
 /// Common static (that is, free-standing) functions, not part of an object hierarchy.
 
 namespace Slic3r { namespace GUI {
 
+enum class OS { Linux, Mac, Windows } ;
+// constants to reduce the proliferation of macros in the rest of the code
+#ifdef __WIN32
+constexpr OS the_os = OS::Windows;
+#elif __APPLE__
+constexpr OS the_os = OS::Mac;
+#elif __linux__
+constexpr OS the_os = OS::Linux;
+#endif
+
+#ifdef SLIC3R_DEV
+constexpr bool isDev = true;
+#else
+constexpr bool isDev = false;
+#endif
+
 /// Performs a check via the Internet for a new version of Slic3r.
-/// If this version of Slic3r was compiled with SLIC3R_DEV, check the development 
+/// If this version of Slic3r was compiled with -DSLIC3R_DEV, check the development 
 /// space instead of release.
 void check_version(bool manual = false);
 
+const wxString var(const wxString& in);
+
+/// Always returns path to home directory.
+const wxString home(const wxString& in = "Slic3r");
+
 }} // namespace Slic3r::GUI
 
 #endif // MISC_UI_HPP