Microsoft KB Archive/162682

= PRB: Visual FoxPro form is inaccessible with Foundation READ =

Article ID: 162682

Article Last Modified on 12/6/2004

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APPLIES TO


 * Microsoft Visual FoxPro 3.0 Standard Edition
 * Microsoft Visual FoxPro 3.0b Standard Edition
 * Microsoft Visual FoxPro 5.0 Standard Edition
 * Microsoft Visual FoxPro 6.0 Professional Edition
 * Microsoft Visual FoxPro 7.0 Professional Edition
 * Microsoft Visual FoxPro 8.0 Professional Edition
 * Microsoft Visual FoxPro 9.0 Professional Edition

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This article was previously published under Q162682



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 the behavior
  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

 Click Do Screen on the menu. A FoxPro 2.x style READ screen is displayed. Click the Close me to close the screen. Click Do Form on the menu. A Visual FoxPro form is instantiated and displayed. Click the Close me to try 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. 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.

