The W$FORGET routine causes the ACUCOBOL-GT Terminal Manager to reinitialize itself.
The exact effects of this routine depend on the host machine, but include such things as setting the current screen image to unknown, repositioning the cursor to the last line on the screen, and placing the current screen attribute to unknown. Note that once the current screen image is forgotten, any pop-up windows that you create afterwards will act as if the original screen image were spaces. This may erase some portions of the screen when you close those windows.
The reasons for calling this routine are fairly specialized. This routine allows the window manager to function correctly when the user's screen has been changed in ways that the window manager is unaware of. Since the window manager keeps an exact image of the user's screen, it must manage every change to the screen itself. If it does not, then you must tell it to forget its current screen image. You can use this routine to restart the window manager after a sequence of ANSI-style ACCEPT or DISPLAY statements.