Q33035: History On in Debug Menu Will Not Go through Event Traps

Article: Q33035
Product(s): See article
Version(s): 4.00 4.00b
Operating System(s): MS-DOS
Keyword(s): ENDUSER | buglist4.00 buglist4.00b fixlist4.50 B_BasicCom | mspl13_basic
Last Modified: 8-DEC-1989

The History On feature in the Debug menu in QB.EXE Version 4.00 should
allow you to trace backward and forward through the last 20 statements
executed by your program. However, if the program moves to an
event-trapping subroutine, History On will not record these statements
and will act as if the trap never occurred.

Microsoft has confirmed this to be a problem in QuickBASIC Versions
4.00 and 4.00b and in the QuickBASIC that comes with Microsoft BASIC
Compiler Versions 6.00 and 6.00b for MS-DOS and MS OS/2 (buglist6.00,
buglist6.00b). This problem was corrected in QuickBASIC Version 4.50
and in QBX.EXE of Microsoft BASIC Compiler Version 7.00 (fixlist7.00).

The following is a sample code:

'Turn on History On before running this program, and set a Breakpoint
'either on the last line, or the next-to-last line. By pressing
'SHIFT+F8 (History Back), the program will not step through the trap
'routine, but just step through the FOR..NEXT loop.

ON KEY(1) GOSUB KeyTrap        'Traps the F1 key.
KEY(1) ON
FOR i = 1 TO 100
  PRINT "hello there";
  PRINT i
NEXT
END
KeyTrap:
     PRINT "I'm"
     PRINT "     in"
     PRINT "         a"
     PRINT "            trap!"   'Put Breakpoint here, or on the RETURN.
     RETURN

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