diff --git a/src/slic3r/GUI/GUI_Preview.cpp b/src/slic3r/GUI/GUI_Preview.cpp
index 2d10cd50e..d8f8f2f89 100644
--- a/src/slic3r/GUI/GUI_Preview.cpp
+++ b/src/slic3r/GUI/GUI_Preview.cpp
@@ -506,7 +506,8 @@ void Preview::update_layers_slider_from_canvas(wxKeyEvent &event)
     IMSlider *m_layers_slider = m_canvas->get_gcode_viewer().get_layers_slider();
     IMSlider *m_moves_slider  = m_canvas->get_gcode_viewer().get_moves_slider();
     if (key == 'L') {
-        m_layers_slider->switch_one_layer_mode();
+        if(!m_layers_slider->switch_one_layer_mode())
+            event.Skip();
         m_canvas->set_as_dirty();
     }
     /*else if (key == WXK_SHIFT)
diff --git a/src/slic3r/GUI/IMSlider.cpp b/src/slic3r/GUI/IMSlider.cpp
index d83c08297..12a1ee18d 100644
--- a/src/slic3r/GUI/IMSlider.cpp
+++ b/src/slic3r/GUI/IMSlider.cpp
@@ -705,8 +705,11 @@ bool IMSlider::check_ticks_changed_event(Type type)
 
 
 // switch on/off one layer mode
-void IMSlider::switch_one_layer_mode()
+bool IMSlider::switch_one_layer_mode()
 {
+    if (m_show_custom_gcode_window)
+        return false;
+
     m_is_one_layer = !m_is_one_layer;
     if (!m_is_one_layer) {
         SetLowerValue(m_min_value);
@@ -715,6 +718,7 @@ void IMSlider::switch_one_layer_mode()
     m_selection == ssLower ? correct_lower_value() : correct_higher_value();
     if (m_selection == ssUndef) m_selection = ssHigher;
     set_as_dirty();
+    return true;
 }
 
 void IMSlider::draw_background(const ImRect& groove) {
diff --git a/src/slic3r/GUI/IMSlider.hpp b/src/slic3r/GUI/IMSlider.hpp
index 59d2e2e45..5b6e7ce98 100644
--- a/src/slic3r/GUI/IMSlider.hpp
+++ b/src/slic3r/GUI/IMSlider.hpp
@@ -265,7 +265,7 @@ public:
     void add_code_as_tick(Type type, int selected_extruder = -1);
     void post_ticks_changed_event(Type type = Custom);
     bool check_ticks_changed_event(Type type);
-    void switch_one_layer_mode();
+    bool switch_one_layer_mode();
 
     bool render(int canvas_width, int canvas_height);