OpenWindows

See Staring into the COM Abyss

This is a shell namespace extension that displays a list of opened Windows Explorer windows you have open. It's inspired by the OS/2 stock file dialogs and how they did the same for Workplace Shell windows. If you're the type of person who has a lot of Explorer windows open, and wish you could get to one from a save dialog, this is probably the extension for you.

Shell namespace extensions are one of the hairiest parts of the already pretty baroque COM shell world due to the thin documentation on them and few debugger aids availabile. Good examples are even thinner. Hopefully, this provides an example of a shell extension that does something and has the least amount of untangling layers.

Building

This is a Visual C++ 2010 project. It'll build for x86 and amd64. It's been tested on 2000, ME, XP, Vista, and 10.

The solution builds with VS 2010 and 2019. VC++6 is supported through its own project file. Other versions of VS after 6 should be fine but will likely require building a new project file.

It should run on 98/NT4+ with the IE4+ (preferably 5+) shell used. Windows 95 should be possible but API support gets slightly sketchier there.

Installation

Copy the DLL and TLB somehwere and run regsvr32 OpenWindows.dll.

To uninstall, run regsvr32 /u OpenWindows.dll.

This is going to worm its way into anything with a shell view, so it might cause stability issues. Caveat emptor.

Known issues

The code isn't as 64-bit clean as it should be, and there are some unchecked string handling functions used (2004 was a more innocent time).
The namespace alleges it has a physical manifestation. This is appearantly to appease software that has custom dialogs checking for filesystem presence such as... Microsoft Office. Oops! This is the system temp folder, so a window opened there won't appear. Sorry! (It could be mitigated if we pick an install path...)
We could have an installer which would register it and create paths.
Modern property handling is very, very basic and intended just to appease the tile view subtitles in Vista+. It should probably use fancier behaviour, but for now it delegates as much as it can except the bare minimum to the "classic" way of doing it.
The icon sucks, doesn't it?
There's probably a better way to do a lot of this, but again, it's a lot of cargo culting. Eventually I did find some wrapper for this... after I was well into the MVP. Mea culpa. (They prob wouldn't fit the needs very well, since I suspect most people interested in NSEs want to materialize entities that don't exist in the filesystem. Pascal's code did and provided a good start.)
Enumerate.cpp started from a simple example, so it doesn't use ATL much.

Attributions

See LICENSE.txt.

This is based off of code by Pascal Hurni. I contacted him for clarifying the license of the derived code and he has approved of putting it under the MIT license.

This uses some Microsoft code as a polyfill for full functionality when built with older SDKs.

Source (a DOpus favourites NSE): https://www.codeproject.com/Articles/7973/An-almost-complete-Namespace-Extension-Sample