The Old New Thing

Don't forget, Unicode includes formatting characters which can be used to influence output formatting

September 26, 2013 Sep 26, 2013 09/26/13

Raymond Chen

Consider this simple function: Depending on your screen resolution and font choices, this may end up displaying like this: That line break was awfully unfortunate, stranding the number 2 on a line by itself. (In publishingspeak, this is known as a orphan.) You can't control where the function will insert line breaks, but you can try...

How can I tell that somebody used the MAKEINTRESOURCE macro to smuggle an integer inside a pointer?

September 25, 2013 Sep 25, 2013 09/25/13

Raymond Chen

Many functions and interfaces provide the option of passing either a string or an integer. The parameter is formally declared as a string, and if you want to pass an integer, you smuggle the integer inside a pointer by using the macro. For example, the function lets you load an resource specified by integer identifier by passing the ...

Providing a custom autocomplete source for an edit control

September 23, 2013 Sep 23, 2013 09/23/13

Raymond Chen

Today's Little Program shows a custom source for autocomplete. It's nothing exciting, but at least's it's something you can use as a starting point for your own customizations. We start with a dialog template, whose edit control will be the target of a custom autocomplete. Just for fun, I wrote the program in ATL. Instead of complaining ...

How can I tell that I have a shell folder that represents My Computer?

September 20, 2013 Sep 20, 2013 09/20/13

Raymond Chen

You have in your hands an , and you want to know whether this is an that represents My Computer. There are a few ideas that may occur to you. One is to ask the folder for its current location and compare it to . Okay, we have a lot of moving parts here. Let's look at them one at a time. The function takes an object and asks what folder...

When a program is launched via DDE, and there are multiple servers, which one is used?

September 19, 2013 Sep 19, 2013 09/19/13

Raymond Chen

Although you are more than welcome to stop using DDE (please oh please stop using it), there are still many applications which still use it (cough), and as a result, customers still have questions about it. One customer wanted to know why, if multiple copies of a DDE-based application are running, Windows 7 will send the command to the ...

SubtractRect doesn't always give you the exact difference

September 18, 2013 Sep 18, 2013 09/18/13

Raymond Chen

The function takes a source rectangle and subtracts out the portion which intersects a second rectangle, returning the result in a third rectangle. But wait a second, the result of subtracting one rectangle from another need not be another rectangle. It might be an L-shape, or it might be a rectangle with a rectangular hole. How does this ...

Forcing a file handle closed when it has been opened remotely

September 16, 2013 Sep 16, 2013 09/16/13

Raymond Chen

Today's Little Program closes a file handle that was opened remotely. It builds on previous discussion on how to use the functions. Forcing a network file handle closed does not actually close the handle. This makes it very different from the various "force handle closed" utilities out there. Rather, forcing a network file handle closed...

Why are my posted messages getting lost when the user drags my window around?

September 5, 2013 Sep 5, 2013 09/5/13

Raymond Chen

This question was inspired by an actual customer question, but I changed a lot of it around to make for a more interesting story. (Trust me, the original story was even more boring.) A customer's background thread posted a message to the main UI thread to signal something (details not important). They found that the posted message was never...

Can an x64 function repurpose parameter home space as general scratch space?

August 30, 2013 Aug 30, 2013 08/30/13

Raymond Chen

We saw some time ago that the x64 calling convention in Windows reserves space for the register parameters on the stack, in case the called function wants to spill them. But can the called function use the memory for other purposes, too? You sort of already know the answer to this question. Consider this function: How would a naïve...

How can I write to a file only as long as nobody's looking?

August 29, 2013 Aug 29, 2013 08/29/13

Raymond Chen

A customer wanted to know how to detect that the user has opened Notepad to view a particular file. They had come up with method based on polling and sniffing the Notepad title bar, but they found that it consumed a lot of CPU. (They hadn't noticed yet that it doesn't localize, and that it can trigger false positives since Notepad shows only ...