PRB: Text Box Value Does Not Change If ControlSource Is .NULL.

• Microsoft Visual FoxPro for Windows, versions 3.0, 3.0b, 5.0, 5.0a
• Microsoft Visual FoxPro for Macintosh, version 3.0b

SYMPTOMS

When the ControlSource property of a text box control is set to the custom property of a form and the custom property is .NULL., the text in the control cannot be changed. If the text in the control is edited, the text changes to .NULL. when the control loses focus.

RESOLUTION

Change the class definition in the code below to add the KeyPress method as follows:

   DEFINE CLASS NewTextBox AS textbox
      PROCEDURE KeyPress
      LPARAMETERS nKeyCode, nShiftAltCtrl
              *-- Once the text has changed, set the custom
              *-- property of the form to the text box.
         ThisForm.custom_prop = This.Value
      ENDPROC
   ENDDEFINE

STATUS

Microsoft is researching this problem and will post new information here in the Microsoft Knowledge Base as it becomes available.

MORE INFORMATION

Steps to Reproduce Behavior

1. Create a program using the code below that creates a form with a custom property and two text boxes. The ControlSource of the first text box is set to the form's custom property.

         frmMain = CREATEOBJECT("frmBase")
         frmMain.Show
         READ EVENTS
   

         DEFINE CLASS frmBase AS Form
   

              *-- Set the property to a character type.
              custom_prop = ""
   
              PROCEDURE Init
                  ThisForm.custom_prop = .NULL.
              ENDPROC
   
              PROCEDURE Unload
            CLEAR EVENTS
         ENDPROC
   
             *-- Create the text box that gives the problem.
             ADD OBJECT text AS NewTextBox WITH ;
                Left = 100, ;
                Top = 0, ;
                Width = 250, ;
                Name = "txtText",;
                NullDisplay = ".NULL.",;
                ControlSource = "thisform.custom_prop"
   
            *-- Create another text box to give you something to tab into.
            ADD OBJECT text2 AS TextBox WITH ;
               Left = 100, ;
               Top = 50, ;
               Width = 250, ;
               Name = "txtText2"
         ENDDEFINE
   
         DEFINE CLASS NewTextBox AS textbox
         ENDDEFINE
   
   

2. Run the program and enter text into the first text box.

3. Tab to the next text box.

   The text in the control changes to .NULL.

Keywords          : FxtoolFormdes VFoxMac vfoxwin vfp50abug vfp50bug kbcode
Version           : MACINTOSH:3.0b; WINDOWS:3.0,3.0b,5.0,5.0a
Platform          : MACINTOSH WINDOWS
Issue type        : kbprb