clear screen
open window 400, 150
backcolor 0, 0, 0
clear window

color 250, 120, 0
texto$ = "Hello world! "
l = len(texto$)
dir = 1
do
    release$ = inkey$(.25)
    if mouseb(release$) = -1 then
        dir = -dir
    end if
    clear window
    text 100, 90, texto$, "modern30"
    if dir = 1 then
        texto$ = right$(texto$, l-1) + left$(texto$, 1)
    else
        texto$ = right$(texto$, 1) + left$(texto$, l-1)
    end if
loop