This variable has meaning only on graphical systems such as Windows. Some
graphical systems (such as Windows) use a "background brush" when they resize a
window. By default, the background brush color for ACUCOBOL-GT is black ("0",
off, false, no). If you have arranged your default background to be white, you
see a black flash when you resize the window. This does not affect the final
appearance of the window, but is briefly noticeable while the window is being
redrawn.
Set WHITE_FILL to "1" (on, true, yes) to cause ACUCOBOL-GT's background brush to be set
to white instead of black. Doing this also causes the initial screen that
ACUCOBOL-GT paints to be white instead of black.
Note that this variable must be set in the configuration file to be effective. Modifying this variable
with the SET ENVIRONMENT verb has no effect.