diff --git a/include/wx/mdi.h b/include/wx/mdi.h
index 37f0fa5208..6425de2253 100644
--- a/include/wx/mdi.h
+++ b/include/wx/mdi.h
@@ -176,6 +176,11 @@ public:
     // level windows too
     virtual bool IsTopLevel() const { return false; }
 
+    // In all ports keyboard navigation must stop at MDI child frame level and
+    // can't cross its boundary. Indicate this by overriding this function to
+    // return true.
+    virtual bool IsTopNavigationDomain() const { return true; }
+
 protected:
     wxMDIParentFrame *m_mdiParent;
 };
diff --git a/include/wx/toplevel.h b/include/wx/toplevel.h
index bf8123e5ab..28a56fe596 100644
--- a/include/wx/toplevel.h
+++ b/include/wx/toplevel.h
@@ -282,6 +282,7 @@ public:
     // override some base class virtuals
     virtual bool Destroy();
     virtual bool IsTopLevel() const { return true; }
+    virtual bool IsTopNavigationDomain() const { return true; }
     virtual bool IsVisible() const { return IsShown(); }
 
     // event handlers
diff --git a/include/wx/window.h b/include/wx/window.h
index 07f1f084bb..31ffe5332b 100644
--- a/include/wx/window.h
+++ b/include/wx/window.h
@@ -1422,6 +1422,15 @@ public:
     virtual wxWindow *GetMainWindowOfCompositeControl()
         { return (wxWindow*)this; }
 
+    // If this function returns true, keyboard navigation events shouldn't
+    // escape from it. A typical example of such "navigation domain" is a top
+    // level window because pressing TAB in one of them must not transfer focus
+    // to a different top level window. But it's not limited to them, e.g. MDI
+    // children frames are not top level windows (and their IsTopLevel()
+    // returns false) but still are self-contained navigation domains as well.
+    virtual bool IsTopNavigationDomain() const { return false; }
+
+
 protected:
     // helper for the derived class Create() methods: the first overload, with
     // validator parameter, should be used for child windows while the second
diff --git a/src/common/containr.cpp b/src/common/containr.cpp
index 910804bc4d..2fda844c96 100644
--- a/src/common/containr.cpp
+++ b/src/common/containr.cpp
@@ -475,8 +475,11 @@ void wxControlContainer::HandleOnNavigationKey( wxNavigationKeyEvent& event )
                 wxWindow *focusedParent = m_winParent;
                 while ( parent )
                 {
-                    // we don't want to tab into a different dialog or frame
-                    if ( focusedParent->IsTopLevel() )
+                    // We don't want to tab into a different dialog or frame or
+                    // even an MDI child frame, so test for this explicitly
+                    // (and in particular don't just use IsTopLevel() which
+                    // would return false in the latter case).
+                    if ( focusedParent->IsTopNavigationDomain() )
                         break;
 
                     event.SetCurrentFocus( focusedParent );