BUG: Scrollable Form Displays Improperly on Resize or Scroll (193078)


The information in this article applies to:

  • Microsoft Visual FoxPro for Windows 6.0
This article was previously published under Q193078

SYMPTOMS

If you create a form with the ScrollBars property set to three, when you resize the form the vertical and horizontal scrollbars may alternately appear and disappear. Also, when you attempt to scroll the form after resizing it, the edge of the form that repaints during the scrolling may display a ghosted image with some of the form's controls.

RESOLUTION

As a workaround, you can call the form's Draw method from within the Resize and Scrolled event procedures.

Place the following code in the form's Resize procedure: 

   This.Draw()

Place the following code in the form's Scrolled procedure: 

   LPARAMETERS nDirection
   This.Draw()

Please see the MORE INFORMATION section of this document for details.

STATUS

Microsoft has confirmed this to be a bug in the Microsoft products listed at the beginning of this article.

MORE INFORMATION

You can create a scrollable form in Visual FoxPro 6.0 by setting the form's ScrollBars property to a value of one, two, or three. Scrollbars appear on the form whenever the form is sized such that any of the form's controls are not fully visible.

Steps to Reproduce Behavior

Alternate Appearance and Disappearance of Scrollbars

  1. Run the following code from a program (.PRG) file: 

          PUBLIC oform1
      oform1=NEWOBJECT("form1")
      oform1.Show
      IF .T.
         SUSPEND
         oform1.width = oform1.width - 14
         SUSPEND
         oform1.width = oform1.width + 28
         SUSPEND
         oform1.width = oform1.width + 1
         ON key label f5 oform1.width = oform1.width - 1
      ELSE
         SUSPEND
         oform1.width = oform1.width + 15
      ENDIF

      DEFINE CLASS form1 AS form
         AutoCenter = .T.
         Height = 329
         Width = 614
         ScrollBars = 3
         Caption = "Form1"
         Name = "Form1"

      PROC Resize
         * Remove comment from following line for workaround.
         * This.Draw()
      ENDPROC

      PROC Scrolled
         LPARAMETERS nDirection
         * Remove comment from following line for workaround.
         * This.Draw()
      ENDPROC

      ADD OBJECT Edit1 AS editbox WITH ;
         Height = 316, ;
         Left = 12, ;
         Top = 12, ;
         Width = 604, ;
         Name = "Edit1"

      ENDDEFINE

  2. Press CTRL+M three times to resume the program and resize the form.
  3. Press F5 a few times, pausing between each press. This resizes the form by reducing its width by one pixel each time.
RESULTS: Each time F5 is pressed, each scrollbar appears or disappears alternately. The same thing happens when the form is resized with the mouse.

Incorrect Repaint When Scrolling Form After Resize

  1. Modify the preceding program. Change the IF .T. line to read IF .F..
  2. Run the program.
  3. Press CTRL+M once.
  4. Click the form's vertical scrollbar DOWN ARROW twice with the mouse.
RESULTS: The area of the form just above the bottom edge contains a ghosting of the bottom edge of the edit box. The same thing happens when the form is resized with the mouse.

Demonstration of Workaround

Remove the (*) asterisk character before the This.Draw() code in the Resize and Scrolled procedures in the preceding program example. Repeat the steps in both scenarios to show that the behaviors described in the SYMPTOMS section no longer occur.

REFERENCES

(c) Microsoft Corporation 1998. All Rights Reserved. Contributions by Jim Saunders, Microsoft Corporation.
Modification Type:MajorLast Reviewed:8/4/1999
Keywords:kbbug KB193078
©2002 Microsoft Corporation. All rights reserved.