>Now my question: Is it possible to remove or replace some or all (own) userland menu entries?

Each call to EMPEG_HIJACK_WAITMENU "replaces" the previous definition with the newest one, but the menu labels remain the same..

So, in a word, no.

I am still not 100% happy with the interface, and may completely flip it around someday, such that it triggers an external program and WAITS for it to exit.

..someday..