DOCUMENT:Q156630  21-AUG-1999  [foxpro]
TITLE   :PRB: Incremental Search with Grid Causes Screen Flicker
PRODUCT :Microsoft FoxPro
PROD/VER:5.00
OPER/SYS:
KEYWORDS:

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The information in this article applies to:

 - Microsoft Visual FoxPro for Windows, versions 5.0, 6.0 
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SYMPTOMS
========

The Refresh method of the Grid control does not move the record pointer in the
grid to the selected record when the record pointer is moved from a control
external to the grid. The grid has to get the focus in order for the record
pointer in it to move to the selected record. Because of this problem, an
incremental search routine, involving the grid and another control, causes the
screen to flicker every time a character is entered.

This article describes a way to avoid the screen flicker when using an
incremental search routine with a grid.

WORKAROUND
==========

You can use the LockScreen property of the Form to eliminate most of the screen
flicker. For example, you can make the following modifications to the Form
created in the STEPS TO REPRODUCE BEHAVIOR section below:

1. Create a New Property for the Form and name it lRefreshingGrid. Set the
   property to .F.

2. Change the code in Text1.InterActiveChange event as follows:

         ThisForm.lRefreshingGrid = .T.
         ThisForm.LockScreen = .T.
         SELECT customer
         SEEK UPPER(ALLTRIM(ThisForm.Text1.Value))
         ThisForm.grid1.SetFocus
         ThisForm.text1.SetFocus
         ThisForm.LockScreen = .F.
         ThisForm.lRefreshingGrid = .F.

3. To ensure that the Valid event of the text box does not fire when the focus
   is moved to the grid and then back to the text box, add the following code to
   the Valid event of the text box:

         IF ThisForm.lRefreshingGrid
            RETURN .T.
         ENDIF

STATUS
======

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

MORE INFORMATION
================

Steps to Reproduce Behavior
---------------------------

1. Create a Form, and set the LockScreen property to False (.F.).

2. Add the Customer table, in the home()+"SAMPLES\DATA" folder, to the Data
   Environment. By default, the table is added to the Data Environment with the
   Name "cursor1". Set the Order property of the cursor to "cust_id".

3. Drag the table onto the form to create a grid. Set the Name property of the
   Grid to "Grid1".

4. Add a TextBox control to the form. Make sure that SelectOnEntry property of
   the Textbox control is set to .F. (the default). Add the following code to
   the TextBox control's InterActiveChange event:

         SELECT customer
         SEEK UPPER(ALLTRIM(This.Value))
         ThisForm.Grid1.Refresh

5. Run the Form and type a few characters in the text box.

6. Although the REFRESH method of the grid is being called from
   Text1.InterActiveChangeEvent, the record pointer in the grid does not move to
   the correct record.

7. Now change the code in Text1.InterActiveChange event as follows:

         SELECT customer
         SEEK UPPER(ALLTRIM(This.Value))
         ThisForm.grid1.SetFocus
         ThisForm.text1.SetFocus

8. Repeat step 5.

9. Now the Record Pointer in the grid is moving correctly but there is a lot of
   screen flicker every time a character is entered into the text box.

Additional query words: kbdse VFoxWin Flash

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Keywords          :  
Technology        : kbVFPsearch kbAudDeveloper kbVFP500 kbVFP600
Version           : 5.00

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