The lockup hook is called when the system locks itself up. The following code shows the syntax for a lockup hook function:
BOOL EXPENTRY LockupHook (HAB hab, HWND hwndLockupFrame);
The hab parameter is the application anchor block.
The hwndLockupFrame parameter is the frame window of the lockup panel.
This function has no return value.
All HK_LOCKUP hooks registered with the system are called when the system locks itself up. All HK_LOCKUP hooks must be system hooks, not message queue hooks.
Application programs that create other lockup password input windows by hooking the HK_LOCKUP system hook can use WinUnlockSystem to force the system to unlock when another form of input is detected other than mouse or keyboard. For example, a pen gesture or some voice input or signature recognition.