The default SCREEN window

When the first interactive instruction is reached in a Genero BDL program, a default window named SCREEN is created.

The default SCREEN window can be used to open one or more successive forms; it can also be closed, with the CLOSE WINDOW SCREEN instruction. If the default SCREEN window is not closed, and a new window is created with the OPEN WINDOW command, an empty default SCREEN window will be displayed.

When writing a GUI application, you typically open the main form in the SCREEN window, and display other forms with the OPEN WINDOW name WITH FORM instruction:

MAIN
  DEFER INTERRUPT
  OPTIONS INPUT WRAP
   ...
  OPEN FORM f_main FROM "custfrm"
  DISPLAY FORM f_main 
   ...
END MAIN

The SCREEN window is not visible in TUI mode because program windows are rendered as simple boxes and SCREEN is created without borders. The size of the SCREEN window is 80x25 in TUI mode.