Disabling the Alt-Tab key combination

The simplest way to achieve this is to use the RegisterHotKey function. By calling this function from within your process you take precedence over the O/S. The WM_HOTKEY message that is generated by the specified key combination will be re-directed to the your processes message queue. To block the hotkey, dont process the WM_HOTKEY message that is sent to your queue. Below I have copied a constructor and destructor that demonstrate this action.

// Call the RegisterHotKey function when the application 
// is instantiated to block the ALT-TAB combination
// Note:  The m_nHotKeyID is a int which specifies the hotkey 
//        ID, the hotkey id is programmer defined
 m_nHotKeyID = 100;

 BOOL m_isKeyRegistered = RegisterHotKey(GetSafeHwnd(), m_nHotKeyID,

 ASSERT(m_isKeyRegistered != FALSE);

//lets remove the hotkey block when the application is destroyed
 BOOL m_iskeyUnregistered = UnregisterHotKey(GetSafeHwnd(), m_nHotKeyID);
 ASSERT(m_isKeyUnregistered != FALSE);
There you have it, the simplest way to block the ALT-TAB without writing a VxD.

One last thing, the hotkey block will continue as long as your application is running. When your process terminates the hotkey will return to its original functionality.

This article was originally published on February 4th, 1999

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