Control Panel .CPL Files and Icon Installation

This article describes the relationship of .CPL files and the icons that appear in the Microsoft Windows and Microsoft Windows for Workgroups Control Panel. This article includes information on the following:

• A general description of .CPL files
• How to replace Control Panel icons
• A list of the default .CPL files shipped with Windows
• What to do if you receive a "Cannot Find Components" message
• How to use the Windows 3.1 icons elsewhere
• Multimedia settings in the CONTROL.INI file
• Possible general protection (GP) faults in the Control Panel

Description of .CPL Files

You can add additional icons and functionality to the Control Panel in Windows 3.1 and Windows for Workgroups versions 3.1 and 3.11 by adding "installable" .CPL files. These .CPL files must be located in the Windows SYSTEM directory or the corresponding icon does not appear in the Control Panel. However multimedia .CPL files can be referenced in another directory by specifying a new path in the [MMCPL] section of the CONTROL.INI file.

You should design and structure the .CPL file to conform to the CPLINFO specification as outlined in the Microsoft Windows Programmer's reference. Simply attaching a .CPL extension to a file of unspecified format doesn't work. The CPLINFO specification contains information concerning the icon, application or device name, identification numbers, and other data.

NOTE: If VER.DLL is missing from the WINDOWS or Windows SYSTEM directory, only the 386 Enhanced icon and the Sound icon appear in Control Panel.

Replacement of Control Panel Icons

When you run the Control Panel in Windows 3.1 or Windows for Workgroups (WFWG), some of the icons may not display if the corresponding .CPL file is corrupt or missing. To correct this problem, you must expand the files from the Windows disks back to the Windows SYSTEM directory. Note that the network icon does not display if the network is not properly installed. This is not a problem with the MAIN.CPL, but with the network installation.

Use the following steps to add a missing Control Panel icon:

1. Exit Windows.
2. Copy EXPAND.EXE from your Windows or WFWG disk to your WINDOWS directory.
   
   NOTE: EXPAND.EXE is located on Windows 3.1 disk 3 (both disk sizes), on WFWG 3.1 disk 8 (5.25) or disk 6 (3.5), and on WFWG 3.11 disk 6 (both disk sizes).
3. Put the Windows disk with the correct *.CP_ file in your floppy disk drive. Depending on the Windows version and disk size you have, *.CPL files are located on the following disks:

         Windows 3.1    3.5" Disk   5.25" Disk
         -------------------------------------
         CPWIN386.CP_   Disk 1      Disk 1
         DRIVERS.CP_    Disk 4      Disk 5
         MAIN.CP_       Disk 4      Disk 5
         SND.CP_        Disk 4      Disk 6
   
         WFWG 3.1       3.5" Disk   5.25" Disk
         -------------------------------------
         CPWIN386.CP_   Disk 2      Disk 2
         DRIVERS.CP_    Disk 6      Disk 7
         MAIN.CP_       Disk 3      Disk 5
         SND.CP_        Disk 7      Disk 8
         WFWSETUP.CP_   Disk 2      Disk 2
   
         WFWG 3.11      3.5" Disk   5.25" Disk
         -------------------------------------
         CPWIN386.CP_   Disk 2      Disk 2
         DRIVERS.CP_    Disk 5      Disk 6
         FAX.CP_        Disk 6      Disk 4
         MAIN.CP_       Disk 3      Disk 3
         SND.CP_        Disk 6      Disk 8
   						

4. Type the following at the MS-DOS command prompt
   expand A:\xxxxx.CP_ C:\WINDOWS\SYSTEM\xxxxx.CPL
   where xxxxx is the name of the file and drive A is the drive containing the floppy disk with the .CPL files.
5. Reopen the Control Panel (it is not necessary to exit Windows because the Control Panel performs its search for .CPL files when it initializes).

Default .CPL Files Shipped with Windows 3.1

Windows 3.1 ships with the following four "installable" Control Panel objects. NOTE: The Windows Driver Library disks include an additional .CPL file, SBPMIXER.CPL (file size 25792, dated 2/1/92), for computers with Creative Labs Sound Blaster Pro sound cards. This icon is an audio-mixing board for the Sound Blaster Pro.

"Cannot Find Control Panel Components" Error Message

The Windows 3.1 or Windows for Workgroups 3.1 and 3.11 Control Panel (CONTROL.EXE) may return the following message upon execution: This error usually occurs when the .CPL files cannot be found in the SYSTEM directory, or if the files have become corrupt. First, you should confirm existence of the following .CPL files in your Windows SYSTEM directory: If any file is missing, you need to expand it from your Windows disks. If all files are there, then it is possible that the files are corrupted. In this case you should exit Windows, delete all of the SYSTEM\*.CPL files, then expand each .CPL from your Microsoft Windows disks into your Windows SYSTEM subdirectory, as described in this article.

Using a .CPL File Icon Elsewhere

The Windows version 3.1 Control Panel contains only one icon embedded in the executable file CONTROL.EXE. If an embedded icon from the Windows 3.0 CONTROL.EXE file is used as a replacement icon for a program item, a similar Windows 3.1 icon may be located in one of the Control Panel data files (*.CPL).

Because of the modular structure of the Windows 3.1 Control Panel, most icons that were embedded in earlier versions of the CONTROL.EXE file have been moved to different associated data files located in the SYSTEM subdirectory. These files include CPWIN386.CPL, DRIVERS.CPL, MAIN.CPL, and SND.CPL. To use one of the icons placed in the .CPL files for a program item in Windows 3.1, use the following steps:

1. In Program Manager, select the program item whose icon needs to be changed.
2. From the File menu, choose Properties to open the Program Item Properties dialog box.
3. Choose the Change Icon button.
4. Type the appropriate .CPL filename in the File Name box, then choose the OK button.

Multimedia Settings in the CONTROL.INI

The [MMCPL] section of the CONTROL.INI file contains information which concerns the size and placement of the Control Panel window, the number of iconized applications in the Control Panel, and a path setting for multimedia .CPL files residing outside of the Windows SYSTEM subdirectory. The settings include: In addition Microsoft Windows for Pen Computing may add the following lines to the [MMCPL] file: These entries allow the Control Panel to find .CPL file in subdirectories other than the Windows SYSTEM subdirectory.

GP Faults in Control Panel

If you experience general protection (GP) faults when opening Control Panel, it is likely that one of the .CPL files is corrupted or damaged. Please follow the instructions in the previous section of this article to replace the icon.

Missing Control Panel Icons

If KRNL386.EXE is in the Windows directory instead of, or in addition to, the Windows\SYSTEM subdirectory, one or more of the Control Panel icons may not appear. KRNL386.EXE should be in only the Windows\SYSTEM subdirectory.

"Microsoft Windows Programmer's Reference, Volume3: Messages, Structures, and Macros," version 3.1, pgs. 260, 543-549.

"Microsoft Windows for Pen Computing: Programmer's Reference, Windows Software Development Kit," version 3.1, pgs. 288-289.