Restrict permissions on schema to hide pl/pgsql code

Hi,

I have a situation where customer is using multi-tenant architecture in the
PostgreSQL database i.e. one schema is for one customer. Now, I have
revoked USAGE permissions from user 'B' on schema 'A' so that user B cannot
query on tables in schema A. This is working as expected. But, when my user
is connecting through pgAdmin (pgAdmin 3 in this case), User B can view and
copy the code for functions/procedures/triggers etc. This is critical,
other users should not have ANY access to schema when I revoke usage
permissions from it.

I tried revoking all permissions from pg_proc for user B and then when user
B clicks on any function in schema A an error is thrown (thus, working as
expected). But, I am afraid, revoking privileges on catalog tables is not a
best approach as it will impact using any other functions as well.

Isn't revoking permissions from a schema should take care of this
situation? Kindly guide.