PS Transaction CJ20N - Exit before displaying project?

Hello fellow ABAPers!

I need to insert code before displaying a project in transaction CJ20N. This is both for validation and initialization purposes. Some fields need to be disabled and some fields need to have default values.

I have searched the net but with no luck. I have tried several exits (inserted BREAK-POINTs) but nothing seemed to work.

Is there any exit available for this? How can I proceed?

Any help that would lead to the right direction would be appreciated.

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Kyle