Set up rulers to prevent access to uninitialized variables later.

git-svn-id: svn://localhost/ardour2/branches/3.0@5025 d708f5d6-7413-0410-9779-e7cbd77b26cf

gtk2_ardour/editor.cc

@@ -1241,6 +1241,8 @@ Editor::connect_to_session (Session *t)
 {
 	session = t;
 
+	compute_fixed_ruler_scale ();
+
 	/* there are never any selected regions at startup */
 
 	sensitize_the_right_region_actions (false);