Custom context Menu on version v1.5.23

Hello!

Please, I would like to know if it should be possible to implement custom context menus on previous versions.
I tried to implement it based on the samples from the docs, but it seems that it was not possible on version 1.5.23, because some functions didn’t exist before.

Was it possible in that version? Is there any documentation for older versions?

Thanks!!

You can find any old version at Page Not Found -- Northwoods Software where m is the major version number, n is the minor number, and b is the baselevel.