Oracle Forms

Hello to all,
I have a very tricky problem when opening a form in a multi-form-environment. For our application the ability to open multiple forms independently is very important. So we decided to open them with built-in OPEN_FORM with parameter session_mode set to session, so each form works in its own database session. Depending on user rights it shall also be possible to open a form in read-only-mode. This is only possible with built-in CALL_FORM which has a parameter query_mode, but it does not have a parameter session_mode. Much more, once you opened a form in read-only-mode, every form opened afterwards will be opened in read-only-mode as well. This behaviour can only be changed with ending the application and re-run it.
Did anyone here have similar problems or any ideas how to solve this ?
To explain further : it is not sufficient to step through all the blocks and switch off properties insert_allowed, update_allowed, delete_allowed, because DML-statements can be reside in program units or, even worse, in database packages.
So, any help or hint will be welcome.

Thanks in advance

Kai