The screen "rubbers" aren just a trim - the glass is bonded in all the way round and the trim (called a goal-post trim, as it covers top and sides) are decoration. However, the side parts of the trim are metal impregnated, and the trim needs to be fitted to the glass prior to fitting to the vehicle - the glue then oozes under pressure, grabs the trim and holds it in place. This makes it incredibly difficult to remove in one piece without damaging. Generally, when a screen is replaced, and new trim is fitted. Trying to pry off the the trim will result in the side parts bending and kinking, making it un-reuseable. There is a way to do it using a specialist wiring machine, some skill and a lot of patience, but even then it cannot be guaranteed that the trim will be reusable afterwards.