html :: BSAlert :: is_dismissible
See http://getbootstrap.com/components/#alerts-dismissible
Default is false
.
# Can the alert be dismissed by clicking the close button?
#
# See http://getbootstrap.com/components/#alerts-dismissible
#
# Default is `false`.
var is_dismissible = false is optional, writable
lib/html/bootstrap.nit:374,2--379,49