BUG: Scrollable Form Displays Improperly on Resize or Scroll

   This.Draw()
						

   LPARAMETERS nDirection
   This.Draw()
						

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.