in "status of triggers", 1.8.1 provides new filter option, "show triggers with unacknowledged events". unfortunately, this option is a separate choice from "show all" and "show problems", which works like "show all", thus it does not allow to show only unacknowledged problems.

to solve this problem, this option should be moved to a checkbox state - for example, "show only triggers with unack events", which would work separately from "show all/show problems" dropdown