Hi there,
before opening this as a github issue (maybe it is “works as designed”) I’ll ask here:
After the update to v2.9 of Icinga Web 2 the new date time picking dialogue overlays/blocks the other elements of the form (e.g schedule downtime, ack with expire time)
I would have expected that the dialogue disappears when clicking outside of it or that there is some form of confirm/close button.
I already found out that the picker can be close by hitting enter on the keyboard after I chose a date/time, but I don’t find this very intuitive atm.
Tested in both Chrome and Firefox.
best regards 
