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Q151092: PRB: Mismatched Pushjmp/Popjmp Call Message from Modify Form

Article: Q151092
Product(s): Microsoft FoxPro
Version(s): MACINTOSH:3.0b; WINDOWS:3.0b
Operating System(s): 
Keyword(s): 
Last Modified: 15-DEC-1999

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The information in this article applies to:

- Microsoft Visual FoxPro for Macintosh, version 3.0b 
- Microsoft Visual FoxPro for Windows, version 3.0b 
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SYMPTOMS
========

When you load a Visual FoxPro form for editing, the process stops before the
form appears on the Visual FoxPro desktop and an error dialog box appears
stating:

  "Mismatched pushjmp/popjmp call"

Clicking the OK button causes the Visual FoxPro session to terminate. The
subsequent action depends on the operating system.

In Windows 95, the user is sent back to the Windows desktop. However, the Visual
FoxPro session remains hidden, but does show in the Windows 95 task list if you
press ALT+TAB, and presents a small, modal dialog box when Visual FoxPro for
Windows 3.0b is restarted. This dialog box appears behind the Visual FoxPro
Desktop of the newer session, remaining hidden until the second Visual FoxPro
session is terminated.

In the Windows NT operating system environment, the same error message appears,
and Visual FoxPro 3.0b is terminated with no residual processes.

In the Windows for Workgroups and the Windows 3.1x operating systems, the error
message is the same. Visual FoxPro is terminated and Windows is locked so the
user must use a "Cold" boot, pushing the reset button or power off/on, to resume
normal operations.

In Visual FoxPro for the Macintosh version 3.0b, the error message returned
states

  "Error loading file - Row Source Type - Record <n>. Property value is
  out of bounds"

where <n> is the row number of the offending control in the .scx table.

CAUSE
=====

This behavior occurs when the form has been saved with the Row Source property
of a Listbox or ComboBox containing any command or reference which has more than
254 characters. An example of a command that is too long is an SQL Select
command that has too many characters in the command expression.

While the limit for a command length in Visual FoxPro for Windows 3.0 is 8092
characters, the limit is only 254 characters when the command is a property of a
control on a form.

If the RowSourceType property is "3 - SQL Statement" for either a Listbox or
Combobox control, the actual SQL SELECT command can be keyed into the RowSource
property in the Property Window.

The Property window of the form limits the number of characters keyed into the
box to 254. However, the acceptable length of the string comprising the
SELECT-SQL statement is 253 bytes.

When an incorrect SELECT is the RowSource of the control, the form is saved and
then restored to the desktop with a MODIFY FORM or a DO FORM. Visual FoxPro then
presents an information dialog box stating:

  "Mismatched pushjmp/popjmp call"

WORKAROUND
==========

To work around this behavior, reduce the length of the SQL SELECT statement. If
you have a copy of Visual FoxPro for Windows 3.0, the form can be modified, the
RowSource SELECT statement modified, and the form can be loaded for editing
and/or execution in Visual FoxPro for Windows release 3.0b.

If the method above is unavailable, the .scx table can be loaded into a work area
with a USE command and then browsed. Each control on the form is described in a
row. The control name is located in a memo field named "Objname", and the actual
SELECT statement is in a memo field named "Properties." When the incorrect
statement is found, it can be edited to the correct length and then saved.

STATUS
======

This behavior is by design.

MORE INFORMATION
================

Steps to Reproduce Behavior
---------------------------

1. In the Visual FoxPro Command window, type "MODIFY FORM testerr" (without the
  quotation marks).

2. From the Form Control toolbar, select Listbox ,and click the form to place a
  listbox.

3. Click the right mouse button on the listbox, and select Properties from the
  Context menu. From the Property menu, choose RowSourceType, and select "3 -
  SQL statement."

4. Click the RowSource property in the row above the RowSourceType.

5. In the Property window, type "SELECT . . . SQL command." The program limits
  the statement to 254 bytes, truncating the last word at DESCEND, as follows:

     SELECT ".." + PADR(CDOW(td_end),12) + DTOC(td_end) ;
        + "-.-" + PADR( ALLTRIM(STR( kl_prt_ct )) ;
        + " LEADS ",10) ;
        +IIF(kl_type="P","..Printed "," UNPRINTED") ;
        AS day, td_end,kl_type ;
     FROM trakdate, keylead ;
     WHERE DTOS(td_end)=keylead.kl_code ;
     INTO CURSOR te ;
     ORDER BY td_date DESCENDING

6. From the File menu, select Save, and then close the form.

7. In the Command window, enter the command "MODIFY FORM testerr."

Additional query words: VFoxWin error freeze terminate list box combo

======================================================================
Keywords          :  
Technology        : kbHWMAC kbOSMAC kbVFPsearch kbAudDeveloper kbVFP300bMac kbVFP300b
Version           : MACINTOSH:3.0b; WINDOWS:3.0b

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