Not receiving WM_PAINT message when returning from Security Screen (Ctrl+Alt+Del) in Windows7

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+1 Q:

Not receiving WM_PAINT message when returning from Security Screen (Ctrl+Alt+Del) in Windows7

I need to detect the closing of the security screen, this is the full screen that appears when a user presses Ctrl+Alt+Del under windows. In Xp my application receives an wm_paint message when this screen is closed but under windows 7, a message is not always received, maybe only 25% of the time.

I tried catching the the WM_WTSSESSION_CHANGE message instead but I only receive this message if the user log outs then logs back into their account.

Not sure on the behaviour in Vista as I have only tested this on XP and 7 so far.

+1 A:

Did you call WTSRegisterSessionNotification() for the window/session to receive the subtypes (wParam) of WM_WTSSESSION_CHANGE (WTS_CONSOLE_CONNECT, WTS_CONSOLE_DISCONNECT, WTS_SESSION_LOCK, WTS_SESSION_UNLOCK)? A plain win32 example is at http://support.microsoft.com/kb/310153

It seems WTS_SESSION_UNLOCK should be what you're after.

Ryan 2010-01-08 14:04:10

I should have clarified, the WM_WTSSESSION_CHANGE message is not receieved if the user hits ctrl alt del, then just clicks cancel on the security screen that pops up. If i lock then unlock the account, i successfully receive the message. I think the problem may be something to do with Aero looking at it.

YoungPony 2010-01-08 14:10:39

If the user hits cancel, then the session is never actually locked so it makes sense that you wouldn't receive the WTS_SESSION_UNLOCK message. I don't know how you handle the 'cancel' scenario except for simple focus tracking in the application.

Ryan 2010-01-08 14:15:42

Ok, it is definitely an Aero issue. Reading into it apparently no WM_ messages are sent in this scenario because the windows are rendered differently under aero. see http://social.msdn.microsoft.com/Forums/en-US/vcgeneral/thread/b2e8d0bc-ee1c-4f8d-bcec-f4481418098f

YoungPony 2010-01-08 14:20:57

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Not receiving WM_PAINT message when returning from Security Screen (Ctrl+Alt+Del) in Windows7

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