When a user inserts a CD-ROM into a drive or attaches a USB camera, Windows detects the arrival and starts a process of examining the device or searching the medium. When the user makes a particular choice, they also have the option to make that selection automatic the next unknown device driver download (.exe or .zip) Windows sees that content or device. The dialog shows the result of a user placing a DVD into a DVD reader, in this case the D: drive.
These actions are called Handlers and there are sets of Handlers associated with various types of content. The user can now make their decision and click OK to proceed. The content types available vary with the type of drive selected. Pictures, Music files and Video files are available with any drive. DVD and CD drives can also have “Music CD” or “DVD movie” and Windows Vista adds others like “Video CD movie” to the list.
Mixed content” is the result of file content types falling into more than one of the Pictures, Music files or Video files content types. Note that a CD containing audio tracks is always considered to be a “Music CD” by Windows, regardless of the presence of data tracks. This will contain a selection of applications deemed appropriate for the content found. Thus if Music files and Video files are both discovered on a flash drive, the user will get to choose from the Handlers for “Music files” along with the Handlers for “Video files”. In this case, the user cannot make their selection the default one.
The options available here are limited to actions that can handle any type of files, usually “Open folder to view files” is the only Handler listed here. This enables the user to make that action the default for Mixed content. Certain types of devices do not appear as drive letters in “My Computer”. Many digital cameras and video devices fall into this category. As Windows cannot examine the files on the device to determine content type, it is left to the manufacturer to decide how to proceed.