PRB: Modal Form Flickers When Exiting Form with DBGrid Control

• Microsoft Visual Basic Standard, Professional, and Enterprise Editions, 16-bit and 32-bit, for Windows, version 4.0

SYMPTOMS

Under certain circumstances, unloading a form containing a DBGrid control causes Visual Basic to hang and other open forms to flicker. After hiding the third form of the program, the second form flickers or blinks. Under the 16-bit edition of Visual Basic, an application error follows the blinking, and displays the following error message:

VB caused a general protection fault in module VB.EXE at 000b:000039f3.

CAUSE

The problem is limited to the following combination of circumstances:

• A project contains at least three forms with each form containing the DBGrid control.



• The first form shows a second, modal form. The problem does not occur if the second form is not shown modally.



• A single form creates two or more instances of the original form.

RESOLUTION

There are two possible resolutions to the problem. Either solution prevents the problem from occurring:

• Do not show the second form as a modal form.


- or -


• In the Unload event of the third form, add the following line of code:

  
     Me.Enabled = False 

STATUS

This behavior is by design.

MORE INFORMATION

Steps to Reproduce Problem

1. Create a Visual Basic project with three forms.



2. Add a Command button to Form1. Place the following code in the Click event of the Command button:

   
      Form2.Show 1 




3. Add a Command button to Form2. Place the following code in the Click event of the Command button:

   
      Form3.Show 1 




4. Add a DBGrid control to Form3. Run the project.



5. From Form1, click the Command button to show Form2. From Form2, click the Command button to show Form3. Close Form3.

Additional query words: 4.00 vb4win vb4all

Keywords : PrgCtrlsStd
Version : 4.00 | 4.00
Platform : NT WINDOWS
Issue type :