Just a quick comment. From AC12 on, you can set the reveal/sill depth from your parameter script. On top of that, you can control whether the old-school reveal parameters should be available or not. Refer to the '2.2. Door/Window objects' section of Appendix 'Fix named optional parameters' of the Basic Library Documentation. Start browsing from here:
http://www.graphisoft.com/support/developer/documentation/LibraryDevKit/
Using this you can force the sill depth of your object to 0 if it is not ready for an actual sill depth.
Regards,
Zsolt
Zsolt Táskai
ArchiCAD Development - GDL Team
AC13, AC14 and upwards...