Modifications to custreports.4gl
The MAIN program block has been modified to open a window containing
        the form with a PROGRESSBAR and a MENU, to allow the user
        to start the report and to exit. A new function, cust_report, is added for
        interruption handling. The report definition, the cust_list REPORT block,
        remains the same as in the previous example.
Changes to the 
MAIN program block
            (custreport2.4gl):01 MAIN
02
03   DEFER INTERRUPT
04   CONNECT TO "custdemo"
05   CLOSE WINDOW SCREEN
06   OPEN WINDOW w3 WITH FORM "reportprog"
07
08   MENU "Reports"
09   ON ACTION start 
10      MESSAGE "Report starting"
11       CALL cust_report()
12   ON ACTION exit 
13       EXIT MENU
14   END MENU
15
16   CLOSE WINDOW w3
17   DISCONNECT CURRENT
18
19 END MAINNote: 
- Line 
03prevents the user from interrupting the program except by using theinterruptaction view. - Line 
06Opens the window and form containing thePROGRESSBAR. - Lines 
08thru14define aMENUwith two actions:- start- displays a 
MESSAGEand calls the functioncust_report - exit - quits the 
MENU 
 - start- displays a