The Old New Thing

Code - The Old New Thing

What('s) a character!

January 5, 2007 Jan 5, 2007 01/5/07
Raymond Chen
Norman Diamond seems to have made a side career of harping on this topic on a fairly regular basis, although he never comes out and says that this is what he's complaining about. He just assumes everybody knows. (This usually leads to confusion, as you can see from the follow-ups.) Back in the ANSI days, terminology was simpler. Windows ...

Why can't I GetProcAddress for CreateWindow?

January 2, 2007 Jan 2, 2007 01/2/07
Raymond Chen
Occasionally, I'll see people having trouble trying to for functions like or . Usually, it's coming from people who are trying to write p/invoke signatures, for p/invoke does a under the covers. Why can't you for these functions? Because they're not really functions. They're function-like macros: In fact, as you can see above is ...

The first parameter to VerQueryValue really must be a buffer you obtained from GetFileVersionInfo

December 26, 2006 Dec 26, 2006 12/26/06
Raymond Chen
The documentation for the function states that the first parameter is a "pointer to the buffer containing the version-information resource returned by the function." Some people, however, decide to bypass this step and pass a pointer to data that was obtained some other way, and then wonder why doesn't work. The documentation says that ...

Do not write in-process shell extensions in managed code

December 18, 2006 Dec 18, 2006 12/18/06
Raymond Chen
Jesse Kaplan, one of the CLR program managers, explains why you shouldn't write in-process shell extensions in managed code. The short version is that doing so introduces a CLR version dependency which may conflict with the CLR version expected by the host process. Remember that shell extensions are injected into all processes that use the ...

Why do user interface actions tend to occur on the release, not on the press?

December 16, 2006 Dec 16, 2006 12/16/06
Raymond Chen
If you pay close attention, you'll notice that most user interface actions tend to occur on the release, not on the press. When you click on a button, the action occurs when the mouse button is released. When you press the Windows key, the Start menu pops up when you release it. When you tap the Alt key, the menu becomes active when you ...

Computing listview infotips in the background

December 14, 2006 Dec 14, 2006 12/14/06
Raymond Chen
When the listview control asks you for an infotip, it sends you then notification, and when you return, the result is displayed as the infotip. But what if computing the infotip takes a long time? You don't want to stall the UI thread on a long operation, after all. This is where comes in. If you want to say, "Um, I'm not ready with that ...

Displaying infotips for folded and unfolded listview items

December 13, 2006 Dec 13, 2006 12/13/06
Raymond Chen
When displaying infotips for listview items, you have to deal with both the folded and unfolded case. "Folded" is the term used to describe a listview item in large icon mode whose text has been truncated due to length. When the user selects the item, the full text is revealed, a process known as "unfolding". Take our scratch program and ...

Do not overload the E_NOINTERFACE error

December 8, 2006 Dec 8, 2006 12/8/06
Raymond Chen
One of the more subtle ways people mess up is returning when the problem wasn't actually an unsupported interface. The return value has very specific meaning. Do not use it as your generic "gosh, something went wrong" error. (Use an appropriate error such as or .) Recall that the rules for are that (in the absence of catastrophic errors...