The Old New Thing

May 2013 - The Old New Thing

Posted messages are processed ahead of input messages, even if they were posted later

May 31, 2013 May 31, 2013 05/31/13
Raymond Chen
Regardless of which interpretation you use, it remains the case that posted messages are processed ahead of input messages. Under the MSDN interpretation, posted messages and input messages all go into the message queue, but posted messages are pulled from the queue before input messages. Under the Raymond interpretation, posted messages ...
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The posted message queue vs the input queue vs the message queue

May 30, 2013 May 30, 2013 05/30/13
Raymond Chen
There are multiple ways of viewing the interaction between posted messages and input messages. MSDN prefers to view posted messages and input messages as part of one giant pool of messages in a message queue, with rules about which ones get processed first. I, on the other hand, prefer to think of posted messages and input messages as ...
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What’s the point of SecureZeroMemory?

May 29, 2013 May 29, 2013 05/29/13
Raymond Chen
The Secure­Zero­Memory function zeroes out memory in a way that the compiler will not optimize out. But what's the point of doing that? Does it really make the application more secure? I mean, sure the data could go into the swap file or hibernation file, but you need to have Administrator access to access those files anyway, and you ...
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Why don’t hotkeys for items on my Start menu work when I am in a fullscreen application?

May 28, 2013 May 28, 2013 05/28/13
Raymond Chen
You can set a hotkey on the shortcuts in your Start menu, and Explorer will launch that shortcut when you press the hotkey, but not if you are in a fullscreen application, like when you set Paint into fullscreen mode, or when you are displaying a PowerPoint presentation. Why are shortcut hotkeys ignored when a fullscreen application is running...

What are the scoping rules for variables in nested courtyards?

May 27, 2013 May 27, 2013 05/27/13
Raymond Chen
I dreamed that I had to fix a bug caused by variable redeclaration inside a nested courtyard. Had to move the horses out of the way first. And then it got weird. I won't go into the orchestra rehearsal that turned out to be just a recording played on a loudspeaker in an empty concert hall. Because you wouldn't believe that part...

What happens if I manually post an auto-generated message into my message queue?

May 24, 2013 May 24, 2013 05/24/13
Raymond Chen
As we well know, the window manager generates various messages on-demand rather than posting them into the queue at the time the event occurs. But what happens if you manually post one of these messages, like Post­Message(hwnd, WM_PAINT, 0, 0)? Does that clear the internal flag that says "This window needs a paint message?" Nope. The...
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Even though mouse-move, paint, and timer messages are generated on demand, it’s still possible for one to end up in your queue

May 23, 2013 May 23, 2013 05/23/13
Raymond Chen
We all know that the generated-on-demand messages like WM_MOUSE­MOVE, WM_PAINT, and WM_TIMER messages are not posted into the queue when the corresponding event occurs, but rather are generated by Get­Message or Peek­Message when they detect that they are about to conclude that there is no message to return and the generated-on-...
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How do I get a window back on the screen when it moved far, far away? Windows 7 (and 8) edition

May 22, 2013 May 22, 2013 05/22/13
Raymond Chen
Some time ago, I showed how to get a window back on the screen when it moved far, far away. That technique still works in Windows 7 and 8, but there's an easier shortcut that takes advantage of window arrangement features added in Windows 7. First, you switch to the application by whatever means. Then hit Win+UpArrow to ...

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