No error windows, no dialogs, file is saved.
I click both system Close icon right-top of window, and File-Exit - no reactions.
I thought it was a problem that I unplugged the boards before hibernate at last night, and plugged them back in. The IDE does not see the connected boards and ports.
I pressed Ctrl-R to check the work of the environment and hotkeys - I got a hang on the "sketch compilation" balloon.
If the IDE creates logs in such cases, I can send them for debugging