[Gtk-sharp-list] How to enable or disable a button

[Raúl Moratalla]

Hi, this is a very easy question: how can I enable or disable a button?
I made the following for disable a button nad it works perfect:

btnBeginSearch.State = Gtk.StateType.Insensitive;

But how can I enable it again? I tried other Gtk.Statetype but the 
didn't work.

Cheers,

Raúl