diff --git a/src/slic3r/GUI/GUI_App.cpp b/src/slic3r/GUI/GUI_App.cpp
index 0c786d393..ce889a897 100644
--- a/src/slic3r/GUI/GUI_App.cpp
+++ b/src/slic3r/GUI/GUI_App.cpp
@@ -1649,6 +1649,29 @@ bool GUI_App::OnExceptionInMainLoop()
 }
 
 #ifdef __APPLE__
+// This callback is called from wxEntry()->wxApp::CallOnInit()->NSApplication run
+// that is, before GUI_App::OnInit(), so we have a chance to switch GUI_App
+// to a G-code viewer.
+void GUI_App::OSXStoreOpenFiles(const wxArrayString &fileNames)
+{
+    wxArrayString other_files;
+    std::vector<wxString> gcode_files;
+    const std::regex pattern_gcode_drop(".*[.](gcode|g)", std::regex::icase);
+    for (const auto& filename : fileNames) {
+        boost::filesystem::path path(into_path(filename));
+        if (std::regex_match(path.string(), pattern_gcode_drop))
+            gcode_files.emplace_back(filename);
+        else
+            other_files.Add(filename);
+    }
+    if (! gcode_files.empty()) {
+        // Drag & Dropping a G-code onto PrusaSlicer. Switch PrusaSlicer to G-code viewer mode.
+        //FIXME Switch application to G-code viewer mode?
+        wxMessageBox("PrusaSlicer on early startup", wxString::Format("Switching to G-code viewer for %s", gcode_files.front()), wxICON_INFORMATION);
+        m_app_mode = EAppMode::GCodeViewer;
+    }
+    wxApp::OSXStoreOpenFiles(other_files);
+}
 void GUI_App::MacNewFile()
 {
     m_mac_initialized = true;
@@ -1675,9 +1698,12 @@ void GUI_App::MacOpenFiles(const wxArrayString &fileNames)
             start_new_gcodeviewer(&filename);
     } else if (! gcode_files.empty()) {
         assert(! m_mac_initialized);
+        assert(m_app_mode == EAppMode::GCodeViewer);
         // Drag & Dropping a G-code onto PrusaSlicer. Switch PrusaSlicer to G-code viewer mode.
         //FIXME Switch application to G-code viewer mode?
         wxMessageBox("PrusaSlicer on startup", wxString::Format("Switching to G-code viewer for %s", gcode_files.front()), wxICON_INFORMATION);
+        // Load the G-code into the G-code viewer.
+        this->plater()->load_gcode(paths.front());
     }
     m_mac_initialized = true;
 }
diff --git a/src/slic3r/GUI/GUI_App.hpp b/src/slic3r/GUI/GUI_App.hpp
index 53eef2518..836378d70 100644
--- a/src/slic3r/GUI/GUI_App.hpp
+++ b/src/slic3r/GUI/GUI_App.hpp
@@ -250,6 +250,7 @@ public:
     virtual bool OnExceptionInMainLoop() override;
 
 #ifdef __APPLE__
+    void            OSXStoreOpenFiles(const wxArrayString &files) override;
     // Called if there is no file to open.
     void            MacNewFile();
     // wxWidgets override to get an event on open files.
diff --git a/src/slic3r/GUI/Gizmos/GLGizmoPainterBase.cpp b/src/slic3r/GUI/Gizmos/GLGizmoPainterBase.cpp
index f4e17d44c..88593776d 100644
--- a/src/slic3r/GUI/Gizmos/GLGizmoPainterBase.cpp
+++ b/src/slic3r/GUI/Gizmos/GLGizmoPainterBase.cpp
@@ -177,6 +177,7 @@ void GLGizmoPainterBase::render_cursor_circle() const
 
     glsafe(::glPopAttrib());
     glsafe(::glPopMatrix());
+    glsafe(::glEnable(GL_DEPTH_TEST));
 }