Cancel navigation at onInputProcessing

Hello,

I have an editable table view with the standard prev/next buttons. When the user changes data I want to validate it before it is saved. This is easy for my own events.

If the user changes something and then clicks "prev" or "next", I can see this at onInputProcessing. I could do the necessary checks and I notice that "prev" or "next" was clicked, BUT I cannot cancel the navigation.

Of course I can cancel the navigation using Java Script on the button, but A) I did not create the button and B) the checks are quite complex and I'd prefer to do it in ABAP.

Is there a way to cancel navigation at onInputProcessing? Otherwise I'd have to create my own "prev" and "next" buttons, but this will look ugly.

Thank you

Roland