Article: Q162682
Product(s): Microsoft FoxPro
Version(s): 3.0,3.0b,5.0,6.0
Operating System(s):
Keyword(s): kbvfp kbvfp300 kbvfp300b kbvfp500 kbvfp600
Last Modified: 19-FEB-2002
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The information in this article applies to:
- Microsoft Visual FoxPro for Windows, versions 3.0, 3.0b, 5.0, 6.0
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SYMPTOMS
========
When a Visual FoxPro form is run within a converted FoxPro 2.x application and
program execution falls back to the Foundation READ, then some or all of the
controls on the form do not respond to keyboard or mouse input.
RESOLUTION
==========
Use a READ EVENTS to set up the wait state, rather than a Foundation READ, which
uses a READ VALID.
STATUS
======
This behavior is by design.
MORE INFORMATION
================
In order to create a wait state in FoxPro 2.x, the Foundation READ was used.
This allowed an application using the FoxPro run time to continue to execute
while waiting for user input--selection of a menu option, for example. In Visual
FoxPro, the Foundation READ is no longer necessary, but the wait state must
still be established to create an application, which uses the run time. This is
now done with the READ EVENTS command.
If a Visual FoxPro form is instantiated, either with DO FORM or CREATEOBJECT()
within an application employing a Foundation READ, the form's controls may be
inaccessible. This occurs if program execution is halted at the Foundation READ
(READ VALID command) when the Visual FoxPro form is instantiated.
Steps to Reproduce Behavior
---------------------------
1. Run the following code from a program (.prg) file:
* Beginning of program file
********************************************************************
* This simulates a FoxPro 2.x application with a menu, screen, and
* Foundation READ. A Visual FoxPro form has been added to this also,
* simulating what occurs if such a form is added to an existing
* FoxPro 2.x type application, which is run under Visual FoxPro.
*
SET PROCEDURE TO SYS(16)
lValid = .F. && Sets the Foundation READ variable
* Establish menu
SET SYSMENU TO
DEFINE PAD do_screen OF _MSYSMENU PROMPT "Do Screen"
DEFINE PAD do_form OF _MSYSMENU PROMPT "Do Form"
DEFINE PAD do_exit OF _MSYSMENU PROMPT "Exit"
ON SELECTION PAD do_screen OF _MSYSMENU DO do__screen
ON SELECTION PAD do_form OF _MSYSMENU DO show__form
ON SELECTION PAD do_exit OF _MSYSMENU DO do__exit
* Establish Foundation READ or READ EVENTS
READ VALID lValid && Comment this and
* READ EVENTS && uncomment this for workaround
SET PROC TO
SET SYSMENU TO DEFAULT
PROCEDURE do__screen
DEFINE WINDOW wind1 FROM 1,1 TO 20,30 ;
FLOAT GROW CLOSE SYSTEM TITLE "Read Screen"
ACTIVATE WINDOW wind1
@ 10,8 GET gnChoice DEFAULT 1 ;
FUNCTION '*3 \!Close me' SIZE 3,12
READ
CLEAR WINDOW
ENDPROC
PROCEDURE do__exit
lValid = .T.
CLEAR EVENTS
CLEAR READ ALL
MOUSE CLICK
ENDPROC
PROCEDURE show__form
PUBLIC ox
ox = CREA('form1')
ox.SHOW()
ENDPROC
DEFINE CLASS form1 AS FORM
CAPTION = "VFP Form"
ADD OBJECT command1 AS COMMANDBUTTON WITH ;
TOP = 120, ;
LEFT = 130, ;
HEIGHT = 25, ;
CANCEL = .T. ,;
CAPTION = "Close me"
PROCEDURE command1.CLICK
THISFORM.RELEASE()
ENDPROC
ENDDEFINE
*
* End of program file
2. Click "Do Screen" on the menu. A FoxPro 2.x style READ screen is displayed.
Click the "Close me" button to close the screen.
3. Click "Do Form" on the menu. A Visual FoxPro form is instantiated and
displayed. Click the "Close me" button to attempt to close the form. The
button will not be accessible. Close the form by clicking on the Close [x]
button in the upper right corner or by pressing Ctrl+F4.
4. Select Exit from the menu.
To demonstrate the workaround, comment out the "READ VALID lValid" line in the
above example by starting the line with an asterisk, remove the asterisk from
the beginning of the "* READ EVENTS" line, and rerun the program. The screen
still works as before, and now the "Close me" command button on the form is also
accessible.
REFERENCES
==========
For additional information on the Foundation READ and READ EVENTS, please see
the following article in the Microsoft Knowledge Base:
Q87694 Menu Appears, Then Application Exits to Operating System
Additional query words:
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Keywords : kbvfp kbvfp300 kbvfp300b kbvfp500 kbvfp600
Technology : kbVFPsearch kbAudDeveloper kbVFP300 kbVFP300b kbVFP500 kbVFP600
Version : :3.0,3.0b,5.0,6.0
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