pagelayout_editor, properties_frame.cpp: add missing event.Skip()

wxFocusEvent code **must** skip the event after processing it.

pagelayout_editor/dialogs/properties_frame.cpp

@@ -466,6 +466,7 @@ void PROPERTIES_FRAME::onModify( wxCommandEvent& aEvent )
 void PROPERTIES_FRAME::onTextFocusLost( wxFocusEvent& aEvent )
 {
     m_propertiesDirty = true;
+    aEvent.Skip();      // Mandatory in wxFocusEvent
 }