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A customer asked whether it was okay to use a duplicated handle even after the original handle was closed. Yes. That's sort of why you would duplicate it. Duplicating a handle creates a second handle which refers to the same underlying object as the original. Once that's done, the two handles are completely equivalent. There's no way to know whic...

Suppose you have a function that creates a reference to a COM object: There are a few issues with this design. First of all, it requires that whoever uses your header file must have included first, since that's where is defined. You could solve that problem by putting at the top of , but that creates its own problems. For example, many hea...

A custom template, or possibly a custom hook function.

Today's Little Program locates the × button in the corner of the window and displays a balloon tip pointing at it. We did this some time ago with the help of the message, which is new for Windows Vista. But what if you don't have that message available, say, because you're running on Windows 2000 or Windows XP or (gasp) Windows 9...

The rules of logic no longer apply when you cross the line.

Today's Little Program plays a sound when the Alt+Tab window appears and disappears. The program registers an accessibility event hook for the and events. The Start event fires when an Alt+Tab operation begins, and the End event fires when an Alt+Tab operation completes. As noted in the documentation, you can get spurious End events, so we k...

Feel free to stop using DDE. There was one customer who confessed that they were still using DDE, and they asked for help debugging a DDE problem. They found that sometimes, when their application was launched for DDE, it never received the message. Instead, the function returned . If launched from Explorer, the error message shown to the user ...

Today's Little Program prints all bit strings of length n subject to the requirement that the string have exactly k 1-bits. For example, all bit strings of length 4 with 2 bits set are 0011, 0101, 0110, 1001, 1010, and 1100. Let's write BitString(n, k) to mean all the bit strings of length n with exactly k bits set. Let's look at the last b...

Consider the following program: The program generates a lot of random integers in the range 0..9 and then counts how many are less than 0, less than 1, less than 2, and so on. It also prints how long the operation took in QPC units. We don't really care how big a QPC unit is; we're just interested in the relative values. (We print the number of...

A customer wanted to know whether it was okay to call with the same handle that returned an error last time. In other words, consider the following sequence of events: The customer elaborated: Suppose that the directory contains four files, A, B, C, and D. We expect the following: After returns an error, can we continue to search with th...