Always keep Sequence_Points sorted.

Timeline/Sequence_Point.H

@@ -37,6 +37,19 @@ protected:
     virtual void set ( Log_Entry &e )
         {
             Sequence_Widget::set( e );
+
+            for ( int i = 0; i < e.size(); ++i )
+            {
+                const char *s, *v;
+
+                e.get( i, &s, &v );
+
+                if ( ! strcmp( ":x", s ) )
+                {
+                    _track->sort();
+                }
+
+            }
         }
 
 public: