File Type Associations (part 4)

4. Lock Your File Types

Tech companies used to spend millions trying to get you to buy their products (OK, they still do), but now the race is on to be "the default." Microsoft wants its Live Search web site to be the default search engine in IE, and Google sued Microsoft to try to prevent this before Windows Vista shipped. Companies pay PC manufacturers to preinstall trial versions of their software on all their machines so their products can be the default. And when you install an application on your PC, the installer invariably makes the new program the default for all the file types it supports.

Why is being the default so important? Because people don't change the defaults.

As a result, software companies—Microsoft included—make a habit out of steamrolling over your preferences to promote their own products. Luckily, you have a defense, and it takes place in the Registry.

There are basically two approaches to protecting your file types: you can back them up so they can be restored in case they're ever overwritten, and you can "lock" them, preventing such changes in the first place.

HKEY_CLASSES_ROOT\.txt
HKEY_CLASSES_ROOT\txtfile
HKEY_CLASSES_ROOT\SystemFileAssociations\text

That last one—the one in the SystemFileAssociations branch. And if you want to include other related filename extensions, such as .log, .ini, and .csv (to name a few), you'll want to include those keys as well.

So, if your file type associations for text files ever get wiped out, just double-click your Registry patch backup to restore them.

But a slicker solution is to lock your file types by setting restrictive permissions on the aforementioned keys. That way, no application, no installer, and not even Windows itself can change them unless you unlock them first.

If you want a shortcut, you can use File Type Doctor, introduced in the previous section. Just highlight the file type you want to lock and click the Lock button. File Type Doctor will not only protect the selected filename extension and associated file type with one click, but all linked filename extensions as well.

5. Expand the Scope of Your File Types

To every rule there's an exception, the basic file types system is laid out, with a collection of keys named for filename extensions (e.g., HKEY_CLASSES_ROOT\.jpg) and the corresponding file type keys (such as HKEY_CLASSES_ROOT\jpegfile). As it turns out, there's yet another connection in the Registry that affects your file types.

Many extension keys—like HKEY_CLASSES_ROOT\.jpg—contain values named PerceivedType, which point to subkeys of HKEY_LOCAL_MACHINE\SOFTWARE\Classes\SystemFileAssociations. The keys therein work like ordinary file type keys, but they're much broader in scope. Instead of being linked to one or two filename extensions, a perceived type key could be linked to dozens.

Say you just installed a new image-resizing utility that you'd like to use with a variety of photo formats. But rather than make it the default for those file types, you decide to add a context menu item for each supported file format (e.g., .jpg, .bmp, .png, and so on). Sure, you can do this for each of the 10 or so graphic formats it supports, but it turns out that all you need to do is add it to this key to affect all your image files at once:

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\SystemFileAssociations\image\shell\my_new_
program

					  

By default, the image key shown here is linked to all filename extensions with a PerceivedType set to image, namely .bmp, .dib, .emf, .gif, .ico, .jfif, .jpe, .jpeg, .jpg, .png, .rle, .tif, .tiff, .wdp, and .wmf.

Windows Vista comes with only five perceived type keys (audio, image, system, text, and video) out of the box, but you can add your own to the SystemFileAssociations branch at any time, provided you then link at least one file extension to it by adding a PerceivedType value pointing to your new key. The benefit is that you can use this key to add a custom context menu item that affects a large number of different file types at once. The drawback is that it's one more place you'll have to look to track down a misbehaving or unwanted context menu item.

To break the connection between a filename extension and a perceived type, just delete the PerceivedType value from the extension key. Or, to link up a file type with an existing PerceivedType, create a new string value named PerceivedType in the extension key, and set its contents to the name of the matching perceived type key in the SystemFileAssociations branch.

File Type Doctor  also supports perceived types through its "scope" and "affiliation" features. For instance, if you try to delete a context menu action that's connected through a perceived type, File Type Doctor displays a confirmation box that lists the other filename extensions that will be affected by the change. Likewise, when creating a new action, you can choose the scope; click the Properties button next to the Scope list to display all the extensions tied to the current selection.

While you're digging around the HKEY_CLASSES_ROOT\SystemFileAssociations branch in the Registry, you may find some file extension keys here as well, like HKEY_CLASSES_ROOT\SystemFileAssociations\.png. These look and work just like the extension keys and file type keys in HKEY_CLASSES_ROOT, but they're used primarily to reference the Windows Explorer extensions that were preinstalled with Windows. Why they're here instead of in HKEY_CLASSES_ROOT with the rest of the extensions is not entirely clear, but what is clear is that the SystemFileAssociations branch is yet another place to look for Registry keys that affect file types.

6. Customize Windows Explorer's New Menu

If you right-click an empty area of the desktop or any open folder window and select New, you'll see special list of registered file types that can be created on the spot. Choose one, and Explorer will create a new (usually empty) file with the appropriate filename extension right there. Not surprisingly, you can edit that list, and even make it do more than just create empty files.

Here's the easiest way to remove unwanted items from Explorer's New menu:

If you want to do it by hand, you'll need to look in a few different places in the Registry:

As you can see, it's merely the presence of a ShellNew key that determines whether a file type shows up in Windows Explorer's New menu. (Actually, it's a little more complicated than that, but more on that subject later.)

Command

If you include the full path and filename of a program executable (.exe file), Explorer will launch the program instead of creating a new file. Make sure to include the "%1" parameter  so the target program knows where to create the new file, like this:

c:\windows\system32\notepad.exe "%1"

Consult your application's documentation to see whether any other command-line parameters are needed to create the new document; otherwise, the program may just open and complain that it can't find the (as yet nonexistent) file.

Data

Any text stored in this binary value will be placed into the new file. For instance, the Data value for .rtf files (in HKEY_CLASSES_ROOT\.rtf\ShellNew) contains the text, {\rtf1}, which ensures that the new .rtf file is readable by whatever program you use to open it. Explorer ignores the Data value if either FileName or NullFile is specified.

FileName

This is the full path and filename of a template file—a file to be copied and used for each new document you create—in lieu of creating an empty (zero-byte) file. If you don't include the path, Windows looks in C:\Users\{your_user_name}\AppData\Roaming\Microsoft\Templates as well as C:\Windows\ShellNew for the template file.

Handler

The Class ID (e.g., {CEEFEA1B-3E29-4EF1-B34C-FEC79C4F70AF}) of the shell extension used to create the new file. For example, Windows Shortcuts (.lnk files) use a handler.

IconPath

The full path and filename (plus the icon index) of the icon that appears next to the item in Windows Explorer's New menu.

ItemName

By default, the name of the new file you create is the name of the file type, preceded by the word "New" and followed by the appropriate filename extension; for instance: New Text Document.txt. This value determines the name of the new file, but like MenuText, described next, it must point to a text resource in a .dll file.

MenuText

Unfortunately, this is not what it looks like. Yes, it determines the text that appears in Explorer's New menu, but you can't just type the text here. Instead, it must be a reference to a text resource in a .dll file, such as @%systemroot%\system32\mspaint.exe,-59414.

NullFile

This instructs Explorer to create an empty (zero-byte) file. If none of these other values are present, you need to include the NullFile value, or the file type won't show up in Explorer's New menu.

So, how do you keep applications from recreating the ShellNew keys and continuously cluttering up Explorer's New menu? Adobe Photoshop does this every time it starts, but all it takes is a quick change to the Registry to prevent it from happening again:

You can accomplish pretty much the same thing with File Type Doctor's Lock feature , but that may be overkill if all you want to do is keep unwanted items out of Explorer's New menu.

7. Fix Internet Shortcuts

Customization is fun, but sometimes all you need to do to a file type is fix it when it breaks. Most of the time you can just reinstall the application that originally created it—unless a UserChoice key is in effect, explained in the "The Evils of UserChoice" sidebar—but that doesn't always work.

One file type that's always getting munged is the .url (Internet Shortcut) type, and repairing it can be a little tricky. For one, .url files don't launch your web browser directly; instead, they activate a Windows .dll that does the launching. In essence, it's a two-step process that employs two different file types; the following sequence of Registry keys shows how it works.

As you can see, there are a lot of Registry keys responsible for something as seemingly simple as opening a web address, and all it takes is one missing key, one misplaced quotation mark, or one mangled class ID to break the whole system. And so it goes with the Registry in Windows Vista.