The Old New Thing

How can I detect that my program was run from Task Scheduler, or my custom shortcut, or a service, or whatever

February 28, 2014 Feb 28, 2014 02/28/14

Raymond Chen

Suppose you want your program to behave differently depending on whether it is launched from the Start menu, or by clicking the pinned icon on the taskbar, or by Scheduled Task, or from a service, or whatever. How can a program detect and distinguish these scenarios? The answer is you don't. And you shouldn't try. Instead of trying to guess ...

What does the SEE_MASK_UNICODE flag in ShellExecuteEx actually do?

February 27, 2014 Feb 27, 2014 02/27/14

Raymond Chen

Somebody with a rude name wonders what the flag does. It does nothing. The flag was introduced when porting the Windows 95 shell to Windows NT. It happened further back in history than I have permission to access the Windows source code history database, but I can guess how it got introduced. One of the things that the porting ...

Why are leading digits converted to language-specific digit shapes, but not trailing digits, and how do I suppress the conversion entirely?

February 26, 2014 Feb 26, 2014 02/26/14

Raymond Chen

If you have a string like , and you render it on an Arabic system, you might get ٠١٢٣٤ABCDE67890. The leading digits are rendered as Arabic-Indic digits, but the trailing digits are rendered as European digits. What's going on here? This is a feature known as contextual digit substitution. You can specify whether...

Logging the contents of every message box dialog via automation

February 24, 2014 Feb 24, 2014 02/24/14

Raymond Chen

Today's Little Program logs the contents of every message box dialog, or anything that vaguely resembles a message box dialog. (Since there's no way for sure to know whether a dialog box is a message box or not.) This is the same pattern as the program we wrote last week, but with different guts when the window opens. This time, we see ...

How can I make sure my program is launched only from my helper program and no other parent?

February 21, 2014 Feb 21, 2014 02/21/14

Raymond Chen

Say you have a collection of programs which work together. One of them is the "master" program that runs the show, and it has a bunch of "assistant" programs that it launches to accomplish various subtasks. These assistants are not meant to be run by themselves; they are meant to be run only by the master program. How do you design the ...

What is the programmatic equivalent to unchecking the box to prevent a file from having its contents indexed?

February 20, 2014 Feb 20, 2014 02/20/14

Raymond Chen

A customer wanted to know how they could write a program that automatically checked and unchecked the box that appears on a file's property sheet on the General tab, clicking the Advanced button, and then checking or unchecking the item whose name keeps changing: The checkbox maps to the file attribute formally known as , and informally ...

When will the static control automatically delete the image loaded into it, and when is it the responsibility of the application?

February 19, 2014 Feb 19, 2014 02/19/14

Raymond Chen

If you create a static control with initial contents (for example, by creating a or control in a dialog template), then the static control will load the contents upon creation and destroy the contents upon destruction. So at least in the case where you don't touch the static control, things will work automatically. But once you touch it, ...