diff --git a/include/wx/gtk/window.h b/include/wx/gtk/window.h
index 66171148b8..4db8b9d73f 100644
--- a/include/wx/gtk/window.h
+++ b/include/wx/gtk/window.h
@@ -255,6 +255,8 @@ public:
     // (because they have been validated by a size-allocate) and should
     // be used to report client size
     bool m_useCachedClientSize;
+    // Whether the GtkAllocation and GdkWindow positions are known to be correct
+    bool m_isGtkPositionValid;
 
     // see the docs in src/gtk/window.cpp
     GtkWidget           *m_widget;          // mostly the widget seen by the rest of GTK
diff --git a/src/gtk/window.cpp b/src/gtk/window.cpp
index 4221a1c1d6..f63565a8c5 100644
--- a/src/gtk/window.cpp
+++ b/src/gtk/window.cpp
@@ -2049,6 +2049,7 @@ size_allocate(GtkWidget*, GtkAllocation* alloc, wxWindow* win)
         win->m_y = a.y;
     }
     win->m_useCachedClientSize = true;
+    win->m_isGtkPositionValid = true;
     if (win->m_clientWidth != w || win->m_clientHeight != h)
     {
         win->m_clientWidth  = w;
@@ -2210,6 +2211,8 @@ void wxWindowGTK::GTKHandleRealized()
 
 void wxWindowGTK::GTKHandleUnrealize()
 {
+    m_isGtkPositionValid = false;
+
     // unrealizing a frozen window seems to have some lingering effect
     // preventing updates to the affected area
     if (IsFrozen())
@@ -2365,6 +2368,7 @@ void wxWindowGTK::Init()
     m_clientWidth =
     m_clientHeight = 0;
     m_useCachedClientSize = false;
+    m_isGtkPositionValid = false;
 
     m_clipPaintRegion = false;
 
@@ -2909,11 +2913,14 @@ void wxWindowGTK::DoSetSize( int x, int y, int width, int height, int sizeFlags
         height = m_height;
 
     const bool sizeChange = m_width != width || m_height != height;
+    const bool positionChange = m_x != x || m_y != y;
 
     if (sizeChange)
         m_useCachedClientSize = false;
+    if (positionChange)
+        m_isGtkPositionValid = false;
 
-    if (sizeChange || m_x != x || m_y != y)
+    if (sizeChange || positionChange)
     {
         m_x = x;
         m_y = y;
@@ -3136,7 +3143,37 @@ void wxWindowGTK::DoClientToScreen( int *x, int *y ) const
 {
     wxCHECK_RET( (m_widget != NULL), wxT("invalid window") );
 
-    if (gtk_widget_get_window(m_widget) == NULL) return;
+    if (!m_isGtkPositionValid && !IsTopLevel() && m_parent)
+    {
+        m_parent->DoClientToScreen(x, y);
+        int xx, yy;
+        DoGetPosition(&xx, &yy);
+        if (m_wxwindow)
+        {
+            GtkBorder border;
+            WX_PIZZA(m_wxwindow)->get_border(border);
+            xx += border.left;
+            yy += border.top;
+        }
+        if (y) *y += yy;
+        if (x)
+        {
+            if (GetLayoutDirection() != wxLayout_RightToLeft)
+                *x += xx;
+            else
+            {
+                int w;
+                // undo RTL conversion done by parent
+                m_parent->DoGetClientSize(&w, NULL);
+                *x = w - *x;
+
+                DoGetClientSize(&w, NULL);
+                *x += xx;
+                *x = w - *x;
+            }
+        }
+        return;
+    }
 
     GdkWindow *source = NULL;
     if (m_wxwindow)
@@ -3144,6 +3181,8 @@ void wxWindowGTK::DoClientToScreen( int *x, int *y ) const
     else
         source = gtk_widget_get_window(m_widget);
 
+    wxCHECK_RET(source, "ClientToScreen failed on unrealized window");
+
     int org_x = 0;
     int org_y = 0;
     gdk_window_get_origin( source, &org_x, &org_y );
@@ -3175,7 +3214,37 @@ void wxWindowGTK::DoScreenToClient( int *x, int *y ) const
 {
     wxCHECK_RET( (m_widget != NULL), wxT("invalid window") );
 
-    if (!gtk_widget_get_realized(m_widget)) return;
+    if (!m_isGtkPositionValid && !IsTopLevel() && m_parent)
+    {
+        m_parent->DoScreenToClient(x, y);
+        int xx, yy;
+        DoGetPosition(&xx, &yy);
+        if (m_wxwindow)
+        {
+            GtkBorder border;
+            WX_PIZZA(m_wxwindow)->get_border(border);
+            xx += border.left;
+            yy += border.top;
+        }
+        if (y) *y -= yy;
+        if (x)
+        {
+            if (GetLayoutDirection() != wxLayout_RightToLeft)
+                *x -= xx;
+            else
+            {
+                int w;
+                // undo RTL conversion done by parent
+                m_parent->DoGetClientSize(&w, NULL);
+                *x = w - *x;
+
+                DoGetClientSize(&w, NULL);
+                *x -= xx;
+                *x = w - *x;
+            }
+        }
+        return;
+    }
 
     GdkWindow *source = NULL;
     if (m_wxwindow)
@@ -3183,6 +3252,8 @@ void wxWindowGTK::DoScreenToClient( int *x, int *y ) const
     else
         source = gtk_widget_get_window(m_widget);
 
+    wxCHECK_RET(source, "ScreenToClient failed on unrealized window");
+
     int org_x = 0;
     int org_y = 0;
     gdk_window_get_origin( source, &org_x, &org_y );