Well, the only way I know is to modify the generated Dynpro flow logic. I would call an own module in the LOOP over extract. Inside the module you can check the entry, if it is an old one and make it read only by LOOP AT SCREEN.
The big disadvantage is, ever you regenerate the maintenance view you have to implement the call of the module again. The module itself should be save if you don't regenerate the top include and the function group main program (expert mode).
