Windows 3.1 Application Compatibility (part 1 of 7)

The information in this article applies to:

• Microsoft Windows Software Development Kit (SDK) for Windows version 3.1

SUMMARY

Application Compatibility Document for Windows 3.1

To make Windows version 3.1 better and more robust than Windows version 3.0, Microsoft enhanced and improved many Windows features. Although every effort was made to ensure compatibility with applications developed for Windows version 3.0, some enhancements may affect the operation of these applications -- especially if an application uses features in an undocumented fashion or relies on invalid assumptions about the behavior of Windows.

Microsoft is eager to help you resolve any compatibility problems you may encounter. This document identifies the enhancements that may affect existing Windows version 3.0 applications and explains how you can determine whether your application will run successfully under Windows version 3.1.

Please read each section carefully and use the "Windows 3.1 Compatibility Test" (available separately) as a checklist to ensure that you have carried out the recommended tests. As you complete each test, mark whether your application passed or failed the test. If your application failed a test, please supply comments that will help Microsoft determine the cause of the compatibility problem. If you choose not to carry out a test, please indicate why in the comments section.

When you have completed the Compatibility Test, return it to:

   Windows Compatibility Test
   Microsoft Corporation
   One Microsoft Way
   Building 4
   Redmond, WA 98052-6399

   prod(winsdk) and 31compattest



                   Application Installation Programs
                   =================================

Potential Problem

Your installation program may not correctly add your application's icon to Program Manager or may not correctly save your application's PROGMAN.INI settings.

Tests

Run your installation program in each of the following applicable environments:

• MS-DOS
• MS-DOS command prompt under Windows version 3.1
• Windows using the Run command in the Program Manager's File menu

                               Windows Setup
                               =============
  
  

Potential Problem

Setup may fail to correctly preserve your application's program group files and WIN.INI settings.

Test

Use Setup to install Windows version 3.1 on a computer on which both Windows version 3.0 and your application are already installed. After installation, be sure that your application's WIN.INI settings are correct and that your application runs properly.

                         Shell Application
                         =================

Potential Problem

An application that assumes it is the shell only when it is the first process will not exit Windows correctly when terminated.

Test

Make your application the shell by specifying your application's executable filename with the "shell" setting in the SYSTEM.INI file. Exit Windows and be sure Windows terminates correctly.

Solution

Your application must determine whether it is the shell by doing the following:

1. Check the number of processes running when it starts.

2. If more than one process is running, check the shell setting in the SYSTEM.INI file.

                         Windows Shell Applications
                         ==========================
   
   

DRAG AND DROP

Drag and drop was reimplemented, and Windows now exports the drag-drop functions and message (WM_DROPFILES).

Potential Problem

An application that reverse-engineered the Windows version 3.0 drag- drop protocol may encounter difficulties.

Tests

1. Drag a file from File Manager to your application. Be sure your application opens the proper file.

2. Drag a file associated with your application to Print Manager. Be sure your application opens and prints the proper file.

SYSTEM COLORS

Windows now provides more system colors and user preferences. Users can select separate colors for active and inactive title bar text, button face, button shadow, button text, button highlight, disabled text, highlight, and highlighted text. Different wallpapers and color schemes were added, and the default color scheme is changed.

Potential Problem

An application may not use all colors correctly.

Test

Display your application's windows, dialog boxes, and controls, and check the colors of the active and inactive title bar text, button face, button shadow, button text, button highlight, disabled text, highlight, and highlighted text colors. Use the Control Panel to set each of the following system color schemes:

• System colors set to default.
• System colors set to a nondefault color scheme, such as Arizona.
• System colors set to a random scheme in which you set colors individually. (Don't use the predefined color schemes.)

CARDFILE AND WRITE FILES

The Cardfile file format is changed, and both Cardfile and Write documents can now contain embedded OLE objects.

Potential Problem

Any application that makes assumptions about Cardfile and Write file formats may not be able to read or write to these files correctly.

Tests

1. Use your application to create Cardfile or Write files. Use Windows version 3.1 Cardfile and Write to open and view the files.

2. Use Windows version 3.1 Cardfile and Write to create files containing OLE objects. Be sure your application can open and read the files.

OTHER CONSIDERATIONS

• Path searching is enhanced. When trying to load DLLs, Windows searches directories in the following order: current directory, Windows directory, System directory, application directory, path. The application directory is new for Windows version 3.1.
• Title fonts for Program Manager and desktop icons are changed, and icon titles can now wrap.
• More than one printer can now be installed on a port.
• Control Panel's font installation is enhanced.
• Program Manager automatically reconnects network drives and devices when Windows is restarted.
• File Manager is entirely new for Windows version 3.1. File Manager includes an interface that lets applications add menu items to File Manager menu by using a File Manager extension library.
• Control Panel now provides an interface for adding new Control Panel applications and icons.
• The Startup group contains applications that load whenever Windows is started. For backward compatibility, Windows continues to support the "load" line in the WIN.INI file.
• The [intl] section in the WIN.INI file is enhanced. More date formats and currency symbols are available.
• Desktop spacing can now be changed by a new setting in the WIN.INI file and by the SystemParametersInfo function.