Just in case I forget in future, RAD Studio no longer allows editing a type library directly.
What can be done is to use the tlbimp utility, like so:
tlbimp -I filename.tlb
in order to generate a RIDL file, which can then be edited.
The output is to the current directory, so be sure to change to the specified directory, or use -D to set the output directory.
In 2017, with the release of Delphi 10.2 Tokyo, Embarcadero introduced a specialized implementation of the Observer pattern into the System.Classes unit. While it has been in the wild for 9 years, it remains a "hidden" architecture for many, primarily because it serves as the invisible engine behind LiveBindings. Other than live bindings, you can also use the Observer pattern as a way to update component settings to the Windows registry, an .ini file, or persist it elsewhere.
System.Classes