xfce4-time-out-plugin sometimes locks screen without postpone dialog

"Allow postpone" checkbox is checked, and sometimes i can see postpone dialog, time to time. But when it is not showing it's a disaster.

Plugin version 1.1.0

mentioned in issue #13 (closed)

moved from xfce/xfce4-panel#312 (moved)

mentioned in issue #10

Duplicate of #13 (closed)?

Same on Plugin version 1.1.2