http://bugs.winehq.org/show_bug.cgi?id=58167
--- Comment #19 from Michael Setzer II mikes@guam.net --- Looked at 10.19 changes, and one seems it might have fixed issue with focus loss.
#57569 BeamNG.drive minimizes its window during startup, with UseTakeFocus set to false.
There is one that list Pegasus, but I never noticed that issue.
#58431 Pegasus Mail Changed font (regression)
I generally do always run Pegasus in Full screen mode, and as I stated it would work the first time with the delete key, and then require click on actual delete button with mouse.
Might have been one of the others that fixed it, but those seem to be most likely to me. Thanks.