Problem with Access Violation

I am having a problem (ACCESS VIOLATION) when trying to use a real
number save in a list. The number is to be used in drawing a line in
response to a mouse click.
I have seen in sftalk reference to similar problems, but still can't get
it right. Can someone please tell me clearly what is going on?
The following is some simple code illustrating the problem. It randomly
works !!!
Thank you,
F DiMeo

empty
REQUIRES FPMATH
4 IMPORT: MoveToEx
3 IMPORT: LineTo
page

{ ==== Create a list of real numbers, save addr to temp ===== }

0 value temp
create info falign 25e f, 20e f, 75e f, 0e f,
info faligned to temp
                                           \ info's aligned addr save in
temp

{ =========== utilitiy words for MoveToEx and LineTo ======== }

: myMoveTo HWND GetDC -rot 0 MoveToEx drop ;
: myLineTo HWND GetDC -rot LineTo drop ;

: drawlineA 0 temp f@ f>s myMoveTo 150 180 myLineTo ;

{ =========================================================== }

[SWITCH window-MESSAGES DEFWINPROC
 WM_RBUTTONDOWN RUNS drawlineA \
randomly works, but does draw sometimes!!!
 WM_CLOSE RUN: HWND DestroyWindow DROP 0 ;
SWITCH]

:noname MSG window-MESSAGES ; 4 CB: window-callback

: CREATE-WINDOW ( -- handle )
  0 \
exended style
  Z" simple-window" \ window
classname
  Z" empty " \
window title
  WS_OVERLAPPEDWINDOW \ window style
  0 0 1300 800 \ x y cx cy
  0 \
parent window handle
  0 \
window menu handle
  HINST \
instance handle
  0 \
creation parameter
  CreateWindowEx ;

: REGISTER-CLASS ( ----- )
 Z" simple-window" \ window
classname
  window-callback \ application
callback name
  DefaultClass DROP ; \ DefaultClass
returns hClass

  : SHOW-WINDOW ( handle-----)
    SW_SHOWNORMAL ShowWindow DROP ; \ ShowWindow returns hWnd

  : window ( -- )
       REGISTER-CLASS
       CREATE-WINDOW
       SHOW-WINDOW ;

{ ============== The follwing is the result of a WM_RBUTTONDOWN message
ACCESS_VIOLATION SNAPSHOT +77
          Registers Dstack Rstack
EAX 77E3B543 00000000 77E266FD
EBX DEADBEEF 00000080 0040F14C
%SRC\I386\WIN32\SF\START.F +47
ECX 01010101 00411128 00000001
EDX FFFFFFFF 7FFDF000 004063A0 PASCAL-CALL +33
ESI 77E14BE0 77E992A6 0040F14C
 %SRC\I386\WIN32\SF\START.F +47
EDI FFFFFFFF 0006D08C 0012FFB4
EBP 0012FFB4 000003E6 0040F128
%SRC\I386\WIN32\SF\START.F +11
ESP 00127F2C 7FFDF000 00402100
EFL 00010246 00290000 00000000
EIP 0040308C 00000003 2B000000
===================================================================== }

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Received on Fri Jan 31 2003 - 08:24:57 PST