There’s no need to alter the shipping ABC files.
There’s no need for a template.
see Writing Derived ABC Classes for APPs - ClarionHub
A quick summary of the steps:
Write the derived class
Put it in a folder that ScanABC knows about
Refresh Classes
In Global Properties > Actions etc. :: change the WindowManager to MyDerivedWindowManager
Regenerate and Compile
Later, If you want to enhance your WindowManager replacement
then alter the class as desired
if there are new methods, that you need embeds for
– save, refresh classes, regenerate
Compile (whether there are new methods or not)