Oracle Forms

Hi all,
Has anyone have any good usage of the POST Built-in?

I have a form A (master) calls a second form B (detail). If the user inserted a record in form B then commit the row in form A, otherwise rollback.

The POST Built-in seems to be a perfect way to do it. However, I saw lots of locking issue that are posted here. And some

So, the only other way for me is to commit the record in Form A first before calling form B. This alternative works fine if the user inserted a child record in form B. If not then I have to delete these these master records without child records...

Does anyone have a better way to do this?
Thanks all for you help.

LL