diff --git a/common/gal/cairo/cairo_gal.cpp b/common/gal/cairo/cairo_gal.cpp
index 69ee7f2a86..50cf80820c 100644
--- a/common/gal/cairo/cairo_gal.cpp
+++ b/common/gal/cairo/cairo_gal.cpp
@@ -40,6 +40,8 @@
 
 #include <pixman.h>
 
+#include <id.h>
+
 using namespace KIGFX;
 
 
@@ -1303,6 +1305,17 @@ void CAIRO_GAL::endDrawing()
 }
 
 
+void CAIRO_GAL::PostPaint()
+{
+    // posts an event to m_paint_listener to ask for redraw the canvas.
+    if( paintListener )
+    {
+        wxPaintEvent redrawReqEvent;
+        wxPostEvent( paintListener, redrawReqEvent );
+    }
+}
+
+
 void CAIRO_GAL::ResizeScreen( int aWidth, int aHeight )
 {
     CAIRO_GAL_BASE::ResizeScreen( aWidth, aHeight );
diff --git a/common/gal/opengl/opengl_gal.cpp b/common/gal/opengl/opengl_gal.cpp
index c0150ce79f..1ec6d2d3f9 100644
--- a/common/gal/opengl/opengl_gal.cpp
+++ b/common/gal/opengl/opengl_gal.cpp
@@ -2,7 +2,7 @@
  * This program source code file is part of KICAD, a free EDA CAD application.
  *
  * Copyright (C) 2012 Torsten Hueter, torstenhtr <at> gmx.de
- * Copyright (C) 2012-2018 Kicad Developers, see AUTHORS.txt for contributors.
+ * Copyright (C) 2012-2020 Kicad Developers, see AUTHORS.txt for contributors.
  * Copyright (C) 2013-2017 CERN
  * @author Maciej Suminski <maciej.suminski@cern.ch>
  *
@@ -352,6 +352,17 @@ wxString OPENGL_GAL::CheckFeatures( GAL_DISPLAY_OPTIONS& aOptions )
 }
 
 
+void OPENGL_GAL::PostPaint()
+{
+    // posts an event to m_paint_listener to ask for redraw the canvas.
+    if( paintListener )
+    {
+        wxPaintEvent redrawReqEvent;
+        wxPostEvent( paintListener, redrawReqEvent );
+    }
+}
+
+
 bool OPENGL_GAL::updatedGalDisplayOptions( const GAL_DISPLAY_OPTIONS& aOptions )
 {
     bool refresh = false;
diff --git a/include/gal/cairo/cairo_gal.h b/include/gal/cairo/cairo_gal.h
index 635338193a..af04a6e5ae 100644
--- a/include/gal/cairo/cairo_gal.h
+++ b/include/gal/cairo/cairo_gal.h
@@ -2,7 +2,7 @@
  * This program source code file is part of KICAD, a free EDA CAD application.
  *
  * Copyright (C) 2012 Torsten Hueter, torstenhtr <at> gmx.de
- * Copyright (C) 2012-2019 Kicad Developers, see change_log.txt for contributors.
+ * Copyright (C) 2012-2020 Kicad Developers, see AUTHORS.txt for contributors.
  * Copyright (C) 2017-2018 CERN
  * @author Maciej Suminski <maciej.suminski@cern.ch>
  *
@@ -388,14 +388,7 @@ public:
      * posts an event to m_paint_listener.  A post is used so that the actual drawing
      * function can use a device context type that is not specific to the wxEVT_PAINT event.
      */
-    void PostPaint()
-    {
-        if( paintListener )
-        {
-            wxPaintEvent redrawEvent;
-            wxPostEvent( paintListener, redrawEvent );
-        }
-    }
+    void PostPaint();
 
     void SetMouseListener( wxEvtHandler* aMouseListener )
     {
diff --git a/include/gal/opengl/opengl_gal.h b/include/gal/opengl/opengl_gal.h
index abc9073354..50f83aa538 100644
--- a/include/gal/opengl/opengl_gal.h
+++ b/include/gal/opengl/opengl_gal.h
@@ -2,7 +2,7 @@
  * This program source code file is part of KICAD, a free EDA CAD application.
  *
  * Copyright (C) 2012 Torsten Hueter, torstenhtr <at> gmx.de
- * Copyright (C) 2012 Kicad Developers, see change_log.txt for contributors.
+ * Copyright (C) 2020 Kicad Developers, see AUTHORS.txt for contributors.
  * Copyright (C) 2013-2017 CERN
  * @author Maciej Suminski <maciej.suminski@cern.ch>
  *
@@ -252,14 +252,7 @@ public:
      * posts an event to m_paint_listener.  A post is used so that the actual drawing
      * function can use a device context type that is not specific to the wxEVT_PAINT event.
      */
-    void PostPaint()
-    {
-        if( paintListener )
-        {
-            wxPaintEvent redrawEvent;
-            wxPostEvent( paintListener, redrawEvent );
-        }
-    }
+    void PostPaint();
 
     void SetMouseListener( wxEvtHandler* aMouseListener )
     {