Added on_layout_changed event handler

src/gui/widgets/timeline/timeline-header-container.cpp

@@ -263,6 +263,12 @@ TimelineHeaderContainer::on_remove(Widget*)
   // Do nothing - this is just to keep Gtk::Container happy
 }
 
+void
+TimelineHeaderContainer::on_layout_changed()
+{
+  layout_headers();
+}
+
 bool
 TimelineHeaderContainer::on_expose_event(GdkEventExpose *event)
 { 

src/gui/widgets/timeline/timeline-header-container.hpp

@@ -129,6 +129,8 @@ private:
   /* ===== Events ===== */      
 private:
 
+  void on_layout_changed();
+
   /**
    * An event handler for when the window must be redrawn.
    */