If you look at the declaration, the Sender object is of type TObject, which
is the class from which (almost) all other objects are derived. You're
probably trying to access a property that isn't defined in TObject, like
Text or Caption or something. For this reason, "Sender.Text" will fail, but
if (for example) you know that the sender is of type TEdit, then you could
use "(Sender As TEdit).Text". If you aren't certain that the Sender object
will always be the same type, you can check it with "if (Sender is TEdit)
then ;". See section 5.14.