If you can do it on the server side, there is a TextChanged event.
Go to properties of the radeditor, double click on TextChanged, it will create the code for you as a
function like Editor1_TextChanged. Just fill it in with the call to save.
Like a Data Access Layer call you have implemented, like:
If you need client side, then I guess you need to listen for keyup events. I don't know that one.
Which one do you need?