UI freezes on connection problem (black screen)

If user got connection problem (network or server fail to response) then all UI is freezes with black screen. You can't see app's windows/menu and can't close it at all. Only task manager can close `java` app.

All connection operations must be independent from the UI. E.g. we need to make events base workflow (as example: data threads running by timers, gets data from server and send it back to main UI thread by event on ready).