Configuring Windows Explorer - Sharing Extensions

Configuring Windows Explorer
Sharing Extensions

Many applications don't play fair - they simply steal a file's association without warning you or asking for permission. (Hum, that sounds suspicious.)

Adding Additional Associations
Web Browsers | Audio/Video Players | Image Editors | Word Processors

Adding Additional Associations

The associations between file extensions and specific applications are stored in the registry. From a practical viewpoint, there is no limit as to how many applications can be associated with a given application. However, only one application can be the default which is executed when a selection is double clicked. In order to execute one of the other associated applications, the user simply needs to RIGHT click the file and select the appropriate action (application) from the context menu.

Technically, there are several similar ways to edit these registry values, though the specific details vary slightly depending on which Windows operating system you are using. Basically, from the Windows Explorer menu, you can select something similar to

View / Folder Options... / File Types

and then edit the appropriate file type (from the type column in the right hand pane in Windows Explorer, assuming that the detail view is showing). The actual selections to get there vary somewhat between the operating systems.

Directly editing the registry is virtually identical in each operating system. It also has the advantage that you can locate the keys by either the actual extension or by searching on the file type. In addition, in the earlier operating systems, you must use the registry to edit the context menu strings.

Using this basic procedure, it is possible to have multiple applications actually share a contested extension. In the registry,

Locate the extension in HKCR (HKEY_CLASSES_ROOT)
(for example - HKCR\.txt)
Locate the HKCR key which match the default value found in step one.
(for example HKCR\txtfile)
The context menu options are located under the shell key. The next step is to rename these keys to NOT use generic terms like Open, Edit, or Play. Instead, use more specific terms like Edit with Notepad, Browse in IE, and Play via mplayer. Advoid using the ambiguous term Open at all costs.
Sometimes the shell verbs have a default value. When present, the default value is what is displayed in the context menu. In those cases, the default value must also be modified.
Using the existing keys as examples, add as many additional keys as you want, usually one for each application which you want to associate with that extension.
If the default value of the shell key matches one of its sub-keys, then the associated command is executed when a file of that type is double clicked.

Web Browsers

It pretty obvious that web browsers are willing to steal htm and html. I discuss this in more detail in BrowserWars - Default Browser.

Audio/Video Players

Windows Media Player redefines numerous registry associations. Of special importance are

HKCR\AudioCD\shell - used when a CD is inserted
HKCR\cdafile\shell - used when you double click on a specific track (*.cda file)

.cda -> cdafile   play (the cdrom default) is changed
  from C:\WIN98\cdplayer.exe -play %1 
  to   "C:\Program Files\Windows Media Player\wmplayer.exe"  /Play "%L"


AudioCD   play (the cdrom default) is changed
  from C:\WIN98\cdplayer.exe /play %1 
  to   "C:\Program Files\Windows Media Player\wmplayer.exe" /device:AudioCD "%L"

This is actually a problem. Even though wmplayer has better features than cdplayer, it is definitely the inferior product since it causes audible skips and repeats as you actually use your computer. I strongly suggest changing your default back to cdplayer or to another application which requires the use of audio cable.

Some other extensions which should be shared

QuickTime AIFF files - .aif .aiff .aifc
.asf .asx .au .avi .cda .ivf .snd .wav .wax .wm .wma .wmd .wmp .wms .wmv .wmx .wmz .wvx
midi - .mid . midi .rmi
mpeg - .m1v .m3u .mp2 .mp2v .mp3 .mpa .mpe .mpeg .mpg .mpv2

Image Editors

.gif and .jpg are hijacked by numerous programs, including web browsers, editors, browsers, and the like.

Normally, .jpg, .jpe, and .jpeg point to the same registry key - HKCR\jpegfile.

Word Processors

Both MS Word and WordPerfect what exclusive access to .doc files.

Author: Robert Clemenzi - clemenzi@cpcug.org