Lazarus sometimes starts and leaves a remanent of the start splash screen up.
See link (screenshot).
It is "on top" of all windows, including non-Lazarus windows.
It doesn't always happen. But when it does, several re-starts don't seem to get away from it.
(Recipe: quit, start up various other apps, re-try. This works 1 time in 4).
Mac OS 10.14
(In this instance it is the Ultibo variant of Laz, but I have this occur with the standard Mac version as well).
(PS: In the current instance of Laz, I can't quit the program - at least I can save my files, so I'll force quit).
https://www.dropbox.com/s/9ef16ork73qztgl/AnnoyingLazarusSplashWindow.jpg