Subclassing and Hooking with Visual Basic

Description

The WH_SHELL hook is a notification hook. That is, you can use it to notify an application of actions occurring to it, either through user intervention or through a change in the system’s state. Examples of user intervention include a user minimizing a window, pressing an application command button on the mouse or keyboard, or even activating a window.

Tip

Newer keyboards and mice can include extra application buttons. These extra buttons allow the user to open applications, control media applications, and open and control Internet browsers. Using this hook, an application developer can add support for these new application buttons to one or more of her applications.

Examples of a change in system state include a change in the keyboard language, a change in the accessibility state, or the system redrawing the window title text in the task bar. The following is a complete list of events for which the WH_SHELL hook can provide notification:

HSHELL_ACCESSIBILITYSTATE

The accessibility state has changed. This is a notification for Windows 2000 and greater operation systems.

HSHELL_ACTIVATESHELLWINDOW

The shell should activate the next application’s main window in the Z-order of current windows.

HSHELL_APPCOMMAND

The user has pressed an application command button on the mouse or on the keyboard and the application did not handle this command button event. An application command button can either be extra buttons added to a keyboard, usually used to control multimedia ...