In versions before 10.5.0, the DESTROY statement was ignored when the statement applied to the main screen, preventing the main screen from being destroyed under any circumstance. Starting with version 10.5.0, destruction of the main application window by the DESTROY statement occurs by default when the handle for the main application window is destroyed. The program runs without a canvas until a new user-defined canvas or a default character-screen is created.
The IGNORE_DESTROY_MAIN_CANVAS configuration variable enables you to switch the behavior of the DESTROY statement back to the behavior in versions 10.4.1 and earlier, thus preventing the main application window from being destroyed.
In the runtime configuration files, set IGNORE_DESTROY_MAIN_CANVAS to 1 (true) to ignore an attempt to destroy the main screen. Set IGNORE_DESTROY_MAIN_CANVAS to 0 (false - default value) to allow the main screen to be destroyed.