FILE: Gridtest.exe: Grid Does Not Refresh Properly

• Microsoft Visual FoxPro for Windows, versions 5.0, 5.0a

SUMMARY

When you use a grid, based on two data sources, the grid may not display properly when you navigate the master table with a custom toolbar while the focus on the main form is in the grid.

The sample file Gridtest.exe contains an example that demonstrates this problem.

The following file is available for download from the Microsoft Software Library:

 ~ Gridtest.exe (size: 35143 bytes) 

   ARTICLE-ID: Q119591
   TITLE     : How to Obtain Microsoft Support Files from Online Services

MORE INFORMATION

Symptoms

Under the following conditions, a grid based on two tables will not display the correct data:

• Focus is on the grid making one of the grid cells active.
• A toolbar button that skips to the next or previous record is clicked.
• The number of records in the grid exceeds the number of records that may be displayed.
• The grid is scrolled.

Resolution

Here are two possible workarounds:

• In the Click events of the navigation buttons on the toolbar, set the focus on the main form to an object other than the grid. This is demonstrated in the sample file with the form called Works. An example of the code is as follows:

        _SCREEN.ACTIVEFORM.txtF1.SETFOCUS
         SELECT TBL1
         SKIP 1
        _SCREEN.ACTIVEFORM.REFRESH
  

  (txtF1 is the name of a visible object on the form)

  -or-

• Create a button on the main form that executes the following code:

        THISFORM.GRID1.REFRESH
  

  (Grid1 is the name of the grid)

  Executing the refresh from a button on the custom toolbar does not solve the problem.

  See step 6 under Steps to Reproduce Behavior for this workaround.

Status

Microsoft has confirmed this to be a bug in the Microsoft products listed at the beginning of this article. We are researching this bug and will post new information here in the Microsoft Knowledge Base as it becomes available.

Steps to Reproduce Behavior

1. Using the sample file run the form named Broken.

2. Click the Next button located on the form. All the visible cells in the first column of the grid should contain the number 2. Note that if the grid is scrolled with either the scroll thumb or scroll arrows, all the grid columns display correctly. The example below demonstrates how the data should be displayed in the grid. The last row will not be visible.

         TBL2.F1   TBL2.F2   TBL3.F2   TBL3.F3
         -----------------------------------------
   
         2         a         a         Red
         2         b         b         Blue
         2         c         c         Green
         2         d         d         Yellow
         2         e         e         Brown
   
   

3. Click in any cell of the grid. The grid now has focus on the form.

4. Click the Previous button on the Toolbar, not the form.

5. Scroll down the grid with the scroll thumb or slider. All the records in the third column (TBL3.F2) will contain the letter "a." "Red" appears in all the records of the fourth column (TLB3.F3). Using the scroll thumb, scroll arrows, or clicking in one of the grid cells does not cause that cell to refresh properly.

   What should be displayed is the example shown in step 2 above with the number 1 in the first grid column for all rows.

6. Make sure that the focus is not in either the third or fourth grid column, and then click the Grid Refresh button on the form. The grid should now be back to normal. If one of the cells in the third or fourth column had focus, it will not refresh, but all the others will. This step implements the second workaround described in the Resolution section above.

7. Click in one of the grid cells, and then click the Next button on the toolbar. The grid should move so that the number 2 is in the first column (TBL2.F1). The data in the third and fourth columns should be correct. Refer to the grid in step 2 above. Note that the last row is not visible.

8. Scroll the grid using the down scroll arrow. Note the values in the third and fourth columns for the first visible record when you finish scrolling.

   If the scroll down was stopped, with only the last two records displayed, and then the up scroll arrow is clicked, all the records displayed from TBL3 will have the correct information. The example below demonstrates how the data should be displayed in the grid.

         TBL2.F1   TBL2.F2   TBL3.F2   TBL3.F3
         --------------------------------------
   
         2         a         d         Yellow
         2         b         d         Yellow
         2         c         d         Yellow
         2         d         d         Yellow
         2         e         e         Brown
   
      If only the last record was visible when scrolling down stopped, then
      all the records will contain an "e" in the third column (TBL3.F2)
      and "Brown" in the fourth column (TBL3.F3) of the grid when
      scrolling up.
   
   

9. Modify the GridTtest.pjx sample project and examine the code in the forms and visual classes.