How can I detect whether the Game Bar is covering my window?

Raymond ChenJune 29, 2016Jun 29, 201606/29/16

Pressing the Win+G hotkey opens the Game Bar, which lets you record game clips and screenshots. Actually, I use it a lot even for programs that aren't games: It's great for taking video clips of a bug. Anyway, maybe you have a program that wants to know when the Game Bar is on screen. For example, if you're a game, you may want to pause the g

If I have multiple attached keyboards, how can I read input from each one individually?

Raymond ChenJune 27, 2016Jun 27, 201606/27/16

Raw Input is a feature of Windows that lets you obtain keyboard, mouse, or generic HID input. Okay, the generic HID input is nice, but the thing that is interesting today is the fact that the keyboard and mouse input is tagged with the device that generated it. This means that if you have multiple keyboards connected to your computer (say, the

Why is my message queue full of WM_TIMER messages?

Raymond ChenJune 24, 2016Jun 24, 201606/24/16

Dmitry wondered how it's possible for a lot of auto-generated messages to pile up in the message queue. I remarked, "That's a good question, and I didn't provide all the information necessary to answer it. Answering it will take more than two sentences, so I will toss it onto the topic queue." One of my colleagues wrote to me and said, "Hey,

Why does the x64 calling convention reserve four home spaces for parameters even for functions that take fewer than four parameters?

Raymond ChenJune 23, 2016Jun 23, 201606/23/16

In the comments to Can an x64 function repurpose parameter home space as general scratch space?, many people questioned why the full four home spaces are allocated for all functions, even those that have fewer that four parameters. MSDN gives a very brief answer: "This aids in the simplicity of supporting C unprototyped functions, and vararg

Using the Windows::Globalization::Calendar object from a Win32 app

Raymond ChenJune 22, 2016Jun 22, 201606/22/16

The Windows.Globalization.Calendar object is documented as supported for use by both Windows Store apps and desktop apps. The UWP samples repo has a Calendar sample that demonstrates how to use it from a Windows Store app, but how do you use it from a desktop app? That's our motivation for looking at the Windows Runtime ABI. Normally, these o

Peeking inside an IShellItem to see what it’s made of

Raymond ChenJune 20, 2016Jun 20, 201606/20/16

Windows XP introduced the IShell­Item interface which represents an item in the shell namespace. This encapsulates what traditionally is represented by a pair of things, the the IShell­Folder interface and an ITEMID_CHILD. The shell item lets you carry just one object around instead of two. Another way of representing an item in the s

How can I update my WinForms app to behave better at high DPI, or at normal DPI on very large screens?

Raymond ChenJune 17, 2016Jun 17, 201606/17/16

A customer had a WinForms app that was showing its age. It didn't scale itself properly on high-DPI screens, which means that if you ran it on a Surface Pro 4, you got a teeny-tiny window and then you had to go grab your magnifying glass in order to read it. The customer noted, "When the program is run on a large display, it occupies only a ti