PRB: Visual FoxPro form is inaccessible with Foundation READ (162682)

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

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 to close the screen.
3. 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.
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.