Cliente side Message until process finishes.

Hi all,

Is there a way to show a message to the user while plugin is executing?

Cenario:
1. The user clicks on activate button on quote form.
2. My plugin runs and sometimes it takes more then 3 minutes to finish, depends on number of itens in the quote.
2. A message pops up to tell the user to wait until process ends.
4. Process end, message disappear and the quote activates.