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There are a bunch of different ways of asking the window manager to call you when something interesting happens. Some of them are are in response to things that you explicitly asked for right now. The enumeration functions are classic examples of this. If you call and pass a callback function, then that callback is called directly from the enumera...

We saw earlier the importance of waiting for I/O to complete before freeing the data structures associated with that I/O. On the other hand, before you start waiting, you have to make sure that you have something to wait for. A customer reported a hang in waiting for an I/O to cancel, and the I/O team was brought in to investigate. They looked...

Although the x64 calling convention reserves space on the stack as spill locations for the first four parameters (passed in registers), there is no requirement that the spill locations actually be used for spilling. They're just 32 bytes of memory available for scratch use by the function being called. We have a test program that works okay wh...

A customer asked for assistance with the function: I am getting when calling even though all the parameters are valid as far as I can tell. I've narrowed it down to this simple program. First of all, thank you for narrowing the issue down to a minimal program that illustrates the problem. You'd be surprised how often a customer says, "I'...

It's true that the vast majority of the time, people consider the shell shortcut object as synonymous with the file it is normally saved into, shortcuts need not spend their time in a file. You can put a shortcut anywhere you can save a hunk of bytes. Here's a program that creates a shortcut to the file name passed on the command line (make sure ...

If an operation includes as part of its processing sending messages, then naturally the target window for those messages must be processing messages (or more precisely, the thread which owns the target window must be processing messages) in order for the operation to complete. Why? Because processing messages is the only way a window can receive me...

The message is sent to your window in order determine what part of the window corresponds to a particular point. The most common reason for this is that the mouse is over your window. Although triggers most often for mouse activity, that is not the only reason why somebody might want to ask, "What part of the window does this point correspond...

A customer asked the following question: What is the maximum legal value of a resource identifier? Functions like take a as the resource ID, which suggests a full 32-bit range, but in practice, most resource IDs appear to be in the 16-bit range. Is there any particular history/precedent for avoiding large numbers as resource IDs? (I have a progr...

The MSDN documentation for window messages describes what each of the parameters means, but just because it means something doesn't mean that it is that something; it merely means it. But you knew this already. If you have a window handle, you can send it whatever message you like, with whatever parameters you like, even if those parameters contra...

Windows XP employed a number of heuristics to determine which Start menu shortcuts should be promoted when an application is newly-installed. But what if those heuristics end up guessing wrong? You can set the property to to tell the Start menu, "I am not the primary entry point for the program; I'm a secondary shortcut, like a help file." ...