Desktop Items

The most common files on the desktop are application programs and associated documents. However, you’ll also come across special files in the System Folder and elsewhere that are used by the system, the Finder or by other applications.

Persistent Trash

Sometimes, you’ll encounter an icon inside the Trash that simply won’t go away when you choose Special ➡ Empty Trash in the Finder. If the item’s locked you can press Option and try again. However, if this fails, you should check that the item isn’t in use. If it’s a document this can usually be solved by closing the file from within the appropriate application. If this doesn’t work, or the item in question is a folder, you should quit the application that last used it and try again.

A folder persisting after these steps can indicate a problem with your drive’s directory, which can’t be fixed by rebuilding the desktop. Instead, you should try the following:-

• Restart the computer and try again.
• Restart from your Mac OS Installer disc and try again.
• Check your drive with a disc utility.

File Kinds

Selecting View ➡ as List in the Finder presents a view that includes a Kind column, which provides a short description of each item. If you use this view to examine folders in the System Folder you’ll see files that are identified as a Chooser extension, control panel, communication tool, contextual menu plug-in, library or system extension.

As well as applications, documents and these special files you’ll encounter the following:-

Alias

An alias is file that points to another file or folder, allowing you to open the original item from one or more alternative locations. Unlike the item itself, which can occupy any amount of disk space, the alias only occupies a few kilobytes.

• You can create an alias of an item by first selecting the item and then choosing File ➡ Make Alias or pressing ⌘-M.
• The item linked to an alias can be found by selecting the alias and choosing File ➡ Show Original or pressing ⌘-R.
• Ideally, folders such as Apple Menu Items, Startup Items and Shutdown Items in the System Folder should only contain items supplied by Apple or aliases, but not other files.
• An alias of a file or folder shared over a network can provide fast access.

Clipping

A clipping is created when you drag and drop selected material out of the window of a suitable application and onto the desktop. Its Kind is given as a text clipping, picture clipping, sound clipping or, if the dragged item is a URL, an email address or web page location.

• A single clipping file can’t contain a combination of the above data types.
• Clipping files with a Kind of text clipping, picture clipping or sound clipping can be viewed in the Finder by clicking on them. Little memory is required to do this and the content can be copied by selecting Edit ➡ Copy or pressing ⌘-C.
• When you click on an email address or web page location clipping an appropriate Internet application is launched and is then directed to the given address or location.

Desk Accessory (DA)

A DA is an older form of application whose memory allocation is set to 20 K. In modern versions of the Classic Mac OS these tiny programmes behave in the same way as a normal application.

Icons

Most items on the desktop have characteristic icons.The icon resources that describe application and document icons are kept in the application file, while those for a folder are inside an invisible Icon file in the folder itself.

File Icons

When a new application is added to your Mac the Finder looks inside the application file for all the icons that it uses. Usually there’s a whole suite of icons, one for each type of file, often including different kinds of documents, stationery files or preferences files. The Finder then copies these icons and other information into the desktop file and keeps track of the application that goes with them.

When the Finder displays a window containing a file belonging to the application it extracts the appropriate icon from the desktop file, which has been transferred into the machine’s memory at startup. The Finder has to deal with numerous files from several applications at once, so using this method is much quicker than extracting information from individual application files.

To replace a file’s normal icon by a custom icon you can select the file, choose File ➡ Get Info ➡ General Information or press ⌘-I, click on the icon and then paste an alternative image in its place. In doing this, the Use Custom Icon attribute, which you can see with FileTyper or a similar file utility, is made active. The new icon, which is stored in the desktop file, is then used in place of the standard icon.

• To make an icon invisible, just copy the colour of its background (perhaps using a graphics application) and then paste this onto the icon in the Get Info window.
• If a file loses its custom icon, open the document with FileTyper, check the Use Custom Icon box, select Change and close the window. Hopefully, your cherished icon will be restored. If not, try rebuilding the desktop.
• If you add a custom icon to an item that’s displayed in an open window in the Finder it may not be updated until you close the window and open it again
• Custom icons on folders aren’t kept in the desktop file, so they’re not kept in memory. This means that they require disk access, sometimes slowing down the Finder’s display.

Missing File Icons

Files associated with an application can lack the correct icons, which can occur if the appropriate icon suite is lost from the desktop file. Rebuilding the desktop fixes this, but takes time on a large drive. As an alternative, open the application’s Get Info window, highlight the icon, select Copy, followed by Paste and Cut. This forces the Finder to read the icons directly, employing the BNDL resource in the application file, thereby updating the application’s entry in the desktop file.

Icon Vaults

The suite of icons used by an application can be replaced, in whole or part, by an icon vault. This is useful if you want to change icons but are hesitant to modify the actual application with ResEdit.

An icon vault is a special file designed for a specific application. All vaults must be in a folder called Icon Vaults (the name begins with a space) in the System Folder. Once installed you should rebuild the desktop in the normal way. The icons within the vault are then given preference over the standard icons and are transferred into the desktop file.

• Icons from an icon vault are actually in the desktop file, so they don’t slow down the display in the same way as custom icons on folders (see below).

Folder Icons

Most folders in the Mac OS have a standard folder icon. However, you can apply a custom icon by working in the Info window in exactly the same way as you would with a file. The custom icon for a folder is stored as icon resources inside an invisible file called Icon that’s kept inside the folder. Such a file usually has type code of icon and a creator code of MACS.

• The filename Icon actually ends with a CR (carriage return) character.

In Mac OS 8.x or higher these files also contain information used by the system, although this appears to be only related to some (but not all) of the view settings for the folder and your choice of folder actions. Apart from this, the removal of such files doesn’t seem to cause any problems.

• If you can’t change a folder’s custom icon you should throw away the Icon file.

Disks

If you select your startup drive icon on the desktop and choose File ➡ Get Info ➡ General Information or press ⌘-I you’ll see the usual form of Get Info window. This shows the Kind as disk, gives you its Format (usually Mac OS Extended in modern systems), its Capacity and the free space Available.

Other drives or removable media also appear on the desktop when mounted. You can also mount a disk image file, either through the Disk Copy application or by using a self-mounting image file. This kind of disk doesn’t actually exist, although the illusion can be useful.

As with files, disks have attributes that can be modified using a file utility such as FileTyper. When checked these have the following effect:-

Folders

A folder is really an illusion created by the computer. It doesn’t actually contain anything but allows you to see a chosen group of files at a single location. This means that when a file is moved, the disk’s directory is modified but the file actually stays in the same place on the drive.

As with files, folders have attributes that can be modified using a file utility such as FileTyper. When checked these have the following effect:-

Suitcases

A suitcase is a special kind of file, unique to the Classic Mac OS, that’s used to store a collection of resources that are available to the system. Although you can drag resource icons in or out of a suitcase, the process is different to moving files in or out of a folder. Hence the Finder presents a Moving dialogue whilst copying resource icons into a suitcase and then removes the original items.

• You can use ResEdit to examine a suitcase’s resources in detail. However, to be on the safe side, you should always work on a copy of the original suitcase.

The following suitcase types may be encountered:-

Invisible Items

At some stage in your Mac experience you’ll encounter items on your hard disk that are normally invisible, although they may appear in the Open or Save dialogues provided by some utility applications. Such items are created by the system or by other software on your computer.

• You can make most items visible or invisible by using a file utility such as FileTyper.
• Invisible files are usually best left alone, since they can contain registration information for an application. Unfortunately, other such files can be used to convey a virus.

Some of the common invisible items found in Mac OS 9.x are listed below:-

©Ray White 2004.