ExitFox.exe Overcomes "Cannot Quit Visual FoxPro" Error

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The following file is available for download from the Microsoft Download Center:
For additional information about how to download Microsoft Support files, click the following article number to view the article in the Microsoft Knowledge Base: Microsoft scanned this file for viruses. Microsoft used the most current virus-detection software that was available on the date that the file was posted. The file is stored on security-enhanced servers that help to prevent any unauthorized changes to the file. There are two common reasons why the "Cannot Quit Visual FoxPro" error message may be encountered. The first is that there is a READ EVENTS active when the QUIT command is issued. The second is that there is a modal form(s) active when the QUIT command is issued.

In Visual FoxPro 3.x, the QUIT command would cut through a modal form(s) and a READ EVENTS to exit an executable. Although the error could still be encountered if, for instance, the application's CloseBox is clicked when a READ EVENTS is in effect. In Visual FoxPro 5.x or 6.x, the QUIT command will not cut through either a modal form or a READ EVENTS.

The sample files contained in this article both illustrate some possible scenarios where the error message may be encountered and a way around it. Visual FoxPro 5.0, 6.0 or the professional version of Visual FoxPro 3.0 or both are needed to work with these files. Although Visual FoxPro 3.0 users won't likely run into the error message in the situations that are illustrated herein. The Visual FoxPro runtime libraries are not included with the sample files. To run the executable files, the runtime libraries must be present. The steps below will assume that Visual FoxPro 5.0 or 6.0, including the support library, are on the computer in use.

To use the sample files, follow these steps.

1. Place the ExitFox.exe self-extracting executable file in a new folder and double click it to extract the files. ExitFox.exe contains the following files:

      quitfox6.pjx
      quitfox6.pjt        These are the Visual FoxPro 5.x project files.
   
      quitfox5.pjx
      quitfox5.pjt        These are the Visual FoxPro 5.x project files.
   
      quitfox3.pjx
      quitfox3.pjt        These are the Visual FoxPro 3.x project files.
   
      quitfox6.exe        Sample custom exe file - Visual FoxPro 6.x.
      quitfox5.exe        Sample custom exe file - Visual FoxPro 5.x.
      quitfox3.exe        Sample custom exe file - Visual FoxPro 3.x.
   
      quitfox6.mnx
      quitfox6.mnt        The menu files for the VFP 6.0 project.
   
      quitfox6.prg        The main program for the VFP 6.0 project.
   						

   The Visual FoxPro 3.x and 5.x project share the following files:

      quitfox.prg         The main program in both projects.
   
      quitfox35.mnx
      quitfox35.mnt       The menu files for each project.
   						

   All projects share the following files:

      quitfox.scx
      quitfox.sct         The first modal form in each project.
   
      quitfox2.scx
      quitfox2.sct        The second modal form in each project.
   						

   The forms are common to each project. You need to recompile the forms in Visual FoxPro version 3.x before they can be opened. The menu file format was changed between versions 5.x and 6.x so there are different vesions of the menu and the main program that runs the menu for the Visual FoxPro 6.x versus the Visual FoxPro 3.x and 5.x versions. There are no version-specific settings or code in any of the projects. Changes in file formats have necessitated the different copies of the project and menu files. The executables can be rebuilt in each version of Visual FoxPro as desired. Just open the project file for the version in use. Using the same files in both projects will illustrate the difference in behavior between version 3.0, version 5.0 and version 6.0.
2. Run the QuitFox.exe file. It should display the Visual FoxPro screen with a menu containing the Quit and Do Modal Form commands.
3. Try to close the application with the CloseBox in the upper-right corner. The "Cannot Quit Visual FoxPro" error message should appear. This occurs because there is a READ EVENTS in effect. The same behavior happens in QuitFox3.exe. You can use the Quit menu command or F11 to exit the application. Or, if you want to allow the application to be shutdown with the CloseBox, choose the AllowCloseBoxExit menu option. It issues an ON SHUTDOWN CLEAR EVENTS command. Instead of issuing this in a menu option, it could be placed at the beginning of the main program in the project. Then the CloseBox could be used to exit the application without choosing the menu option. This can be disabled by setting the Closable property of _Screen to .F. as is done in the Do Modal Form menu option. _Screen is made closable again in the Destroy method of Modal Form #1. This is where the similarities in quitting the two applications will end.
4. Now choose the Do Modal Form menu option. Modal Form #1 should appear. It can be closed with the CloseBox or the Close Form button. However, try the Quit FoxPro button. The "Cannot Quit Visual FoxPro" error should appear. If you are running QuitFox3.exe, this will exit the application.
5. Next choose the Do Another Modal Form button. Modal Form #2 should appear. Try closing it with the Quit FoxPro button. In quitfox3.exe, this will end the application. Here in quitfox.exe it produces the error message. Now try the Hide Modal Forms & Quit button. This hides the modal forms, which makes them modeless, so the QUIT command will then work. The form can be closed with the CloseBox in the top right corner if quitting is not desired.
6. With Modal Form #1 active, increase the value in the spinner control to 5. There is a timer control on this form. The Interval property is initially set to zero to disable it. With the spinner's value set to 5, click on the Set Timer Interval To Spinner Value button. The timer will now fire in 5 seconds. The timer calls a procedure in the main program that releases all open forms and does a CLEAR EVENTS. The application should now disappear after waiting 5 seconds. As a further test, the second modal form can be displayed before the timer fires. The application will still quit. Although not needed in a Visual FoxPro 3.x executable, this method works there too.
7. Open the source files, and examine the code and settings.

The technique employed here could easily be modified for a multi-user setup where a table on a server holds a value that determines if the application should be ended. The procedure that the timer calls would go out and check that value and determine whether or not to end the application. An administrator could set the value at night, for instance, to log out any users who left for the day with the application running. Once all the users are logged out, the administrator could open the application's tables exclusively and PACK, REINDEX or change their structure.