SCREEN INVALID This command will return a one if the application has been switched out and back in.
Syntax
    Return Integer=SCREEN INVALID()
Returns
a one if the application has been switched out and back in
Example Code
    cls

    set display mode 800,600,32

    set window on

    maximize window

    wait 1000*8

    print "screen invalid "+str$(screen invalid())

    do

    loop

    end
See also
DISPLAY Commands Menu Index