It is a general design principle for .net libraries that you should seal a class unless you deliberately and carefully design it to be extensible.
If a class is unsealed you are basically not able to change it ever again, since someone might have subclassed it and depend on all kinds of internal behavior. So it should only be done very deliberately.
If a class is unsealed you are basically not able to change it ever again, since someone might have subclassed it and depend on all kinds of internal behavior. So it should only be done very deliberately.