The Old New Thing

Display control buttons on your taskbar preview window

February 18, 2013 Feb 18, 2013 02/18/13

Raymond Chen

A tiny control surface.

Debug session: Why is an LPC server not responding?

February 15, 2013 Feb 15, 2013 02/15/13

Raymond Chen

A particular scenario was hanging, and the team responsible for the scenario debugged it to the point where they saw that their X component was waiting for their Y component, which was waiting for Explorer, so they asked for help chasing the hang into Explorer. The team was kind enough to have shared what they've learned so far...

If you can’t find the function, find the caller and see what the caller jumps to

February 14, 2013 Feb 14, 2013 02/14/13

Raymond Chen

You're debugging a program and you want to set a breakpoint on some function, say, netapi32!Ds­Address­To­Site­NameW, but when you execute the bp netapi32!Ds­Address­To­Site­NameW command in the debugger, the debugger says that there is no such function. The Advanced Windows Debugging book says that the bp ...

How do I launch a file as if it were a text file, even though its extension is not .txt?

February 13, 2013 Feb 13, 2013 02/13/13

Raymond Chen

You might have a program that generates log files or other text content with an extension other than . You naturally might want to open these documents in the user's default text editor. You might decide to ask the Windows developer support team, "How can I figure out what program is the handler for text files?" The idea being that once you ...

Display an overlay on the taskbar button

February 11, 2013 Feb 11, 2013 02/11/13

Raymond Chen

Today's "Little Program" displays an overlay on the taskbar button. I've seen some people call this a "badge", but "overlay" is the official term. Start with our scratch program and make the following changes: #include <comip.h> #include <comdef.h> #include <shlobj.h> #include <shellapi.h> _COM_SMARTPTR_TYPEDEF(...

How can I register my context menu command for all file types *except* one, or other complex conditionals?

February 7, 2013 Feb 7, 2013 02/7/13

Raymond Chen

Advanced Query Syntax to the rescue.

Obtaining the parsing name (and pidl) for a random shell object

February 4, 2013 Feb 4, 2013 02/4/13

Raymond Chen

The parsing name for a shell item is handy, because it lets you regenerate the item later. Actually, the pidl for the shell item is even better, because that is the official way of saving and restoring objects. It's the pidl that gets saved in a shortcut, and since shortcuts can be copied around from machine to machine, pidls must be ...

Psychic debugging: Why your IContextMenu::InvokeCommand doesn’t get called even though you returned success from IContextMenu::QueryContextMenu

February 1, 2013 Feb 1, 2013 02/1/13

Raymond Chen

A customer was having trouble with their IContext­Menu implementation. They observed that their IContext­Menu::Query­Context­Menu method was being called, but when the user selected their menu item, IContext­Menu::Invoke­Command was not being called. Given what you know about shell context menus, you can already ...

The somewhat misguided question of whether MapViewOfFile or WriteProcessMemory is faster

January 31, 2013 Jan 31, 2013 01/31/13

Raymond Chen

A customer asked, "Which is faster for copying data from one process to another; or ?" This is one of those "Huh?"-type questions, where the customer has solved half of a problem and is looking for help with the other half, the half that makes no sense. First of all, the question is malformed because does not copy any data at all. It ...

Why doesn’t HeapValidate detect corruption in the managed heap?

January 30, 2013 Jan 30, 2013 01/30/13

Raymond Chen

A customer had a program that was corrupting the managed heap by p/invoking incorrectly. The problem didn't show up until the next garbage collection pass, at which point the CLR got all freaked-out-like. "According to Knowledge Base article 286470, the tool is supposed to catch heap corruption, but it doesn't catch squat." Depending on ...