diff --git a/include/wx/gtk/window.h b/include/wx/gtk/window.h
index 20aa4c181b..4fc6ea6f9e 100644
--- a/include/wx/gtk/window.h
+++ b/include/wx/gtk/window.h
@@ -314,6 +314,7 @@ protected:
                            int width, int height,
                            int sizeFlags = wxSIZE_AUTO);
     virtual void DoSetClientSize(int width, int height);
+    virtual wxSize DoGetBorderSize() const;
     virtual void DoMoveWindow(int x, int y, int width, int height);
     virtual void DoEnable(bool enable);
 
diff --git a/include/wx/window.h b/include/wx/window.h
index 52b6daafc2..6c7930a209 100644
--- a/include/wx/window.h
+++ b/include/wx/window.h
@@ -1679,8 +1679,9 @@ protected:
     // of the left and the right border in the x component of the returned size
     // and the sum of the heights of the top and bottom borders in the y one
     //
-    // NB: this is currently only implemented by wxMSW and wxUniv so far and
-    //     simply asserts in the other ports
+    // NB: this is currently only implemented properly for wxMSW, wxGTK and
+    //     wxUniv and doesn't behave correctly in the presence of scrollbars in
+    //     the other ports
     virtual wxSize DoGetBorderSize() const;
 
     // move the window to the specified location and resize it: this is called
diff --git a/src/common/wincmn.cpp b/src/common/wincmn.cpp
index de643e1050..ac1fbb2f40 100644
--- a/src/common/wincmn.cpp
+++ b/src/common/wincmn.cpp
@@ -736,17 +736,14 @@ wxSize wxWindowBase::GetEffectiveMinSize() const
 
 wxSize wxWindowBase::DoGetBorderSize() const
 {
-    // there is one case in which we can implement it for all ports easily:
-    // do it as some classes used by both wxUniv and native ports (e.g.
-    // wxGenericStaticText) do override DoGetBestClientSize() and so this
-    // method must work for them and that ensures that it does, at least in
-    // the default case)
+    // there is one case in which we can implement it for all ports easily
     if ( GetBorder() == wxBORDER_NONE )
         return wxSize(0, 0);
 
-    wxFAIL_MSG( "must be overridden if called" );
-
-    return wxDefaultSize;
+    // otherwise use the difference between the real size and the client size
+    // as a fallback: notice that this is incorrect in general as client size
+    // also doesn't take the scrollbars into account
+    return GetSize() - GetClientSize();
 }
 
 wxSize wxWindowBase::GetBestSize() const
diff --git a/src/gtk/window.cpp b/src/gtk/window.cpp
index e44324e210..209f7be819 100644
--- a/src/gtk/window.cpp
+++ b/src/gtk/window.cpp
@@ -2643,10 +2643,9 @@ void wxWindowGTK::DoGetClientSize( int *width, int *height ) const
             }
         }
 
-        int border_x, border_y;
-        WX_PIZZA(m_wxwindow)->get_border_widths(border_x, border_y);
-        w -= 2 * border_x;
-        h -= 2 * border_y;
+        const wxSize sizeBorders = DoGetBorderSize();
+        w -= sizeBorders.x;
+        h -= sizeBorders.y;
 
         if (w < 0)
             w = 0;
@@ -2658,6 +2657,17 @@ void wxWindowGTK::DoGetClientSize( int *width, int *height ) const
     if (height) *height = h;
 }
 
+wxSize wxWindowGTK::DoGetBorderSize() const
+{
+    if ( !m_wxwindow )
+        return wxWindowBase::DoGetBorderSize();
+
+    int x, y;
+    WX_PIZZA(m_wxwindow)->get_border_widths(x, y);
+
+    return 2*wxSize(x, y);
+}
+
 void wxWindowGTK::DoGetPosition( int *x, int *y ) const
 {
     wxCHECK_RET( (m_widget != NULL), wxT("invalid window") );