Tamas, (sorry I can't find the 4-th letter of Your name)
The following code works perfectly, no main window show:

LOCAL cdir
cdir = ""
**************************
_screen.Width = 1
_screen.Height = 1
_screen.Top    = -1000 && Here
_screen.Visible = .t.
***********************

cdir = GETFILE("", "Válaszd ki az állományt!")

if len(cdir)=0
close all
quit
endif

USE(cdir)

COPY TO c:\export\ujtabla.dbf TYPE FOXPLUS