[xplorer˛] — The stations of IColumnProvider
home » blog » 7 February 2010

1. The fall
Once upon a time, the windows shell supported generic columns for windows explorer and compliant file managers like xplorer˛. When browsing a folder in detailed view you can right click on the column header and pick which columns you want to see. Instead of the generic filename/size/date information you could see interesting details (properties) like program version, file owner etc. You could sort by these extended properties and use them to filter and locate documents of interest.

The architecture was extensible so people could write their own column handlers and register them with windows explorer. Many useful column shell extensions have appeared, adding details like ID3 tags for music files, EXIF tags for pictures, folder sizes... windows explorer was good and useful.

Then came vista and overnight cancelled this extremely useful idea. No more extended column handlers, just like that! I have seen hints about force majeure but in the end of the day it was out with generic explorer columns, which were replaced with a more complex property handler infrastructure.

All old column handlers were binned. And not just technically because of changes in the programming interface, they were ostracised and banished. The internet was filled with puzzled users and programmers that couldn't believe the change was for real. How cruel and senseless of microsoft... no wonder why vista had such a bad reception, it was full of such rubbish small changes for the worse.

2. The technology
Old style column handlers were registered with the folder (under registry key HKEY_CLASSES_ROOT\Folder\ShellEx\ColumnHandlers). From vista onwards (windows 7 included) such associations are ignored by windows shell. The new property handlers associate some extra bit of information with a particular file type (filename extension). It is no longer possible to have a generic column that for example shows the folder size including its subfolders, or the revision status of your source code repository.

Windows 7 didn't change anything in this regard. Custom columns are still not supported. In their place windows explorer offers some 300(!) columns in detailed view mode, most of which one has no clue what they are for (see pic) and most of the time remain empty because you can't understand which document type they are associated with.

I was just like everybody else resigned to the ill fate that befell on us. Then one day we were discussing this fault in the forum when it occurred to me, what if xplorer˛ takes the role of windows explorer?. The column provider architecture is well documented anyway, how explorer is meant to use them to extract information, so all I had to do was to instantiate registered column handlers and use their IColumnProvider interface to extract their columns. Then we could have the old columns back, even in vista and windows 7!
what are all these columns for?

3. The resurrection
A few weeks down the road and I am proud to give you the latest xplorer˛ that breathes life back to the old-style column handlers. And it works for all windows versions, vista and W7 included. When you select View > Select columns menu, you will see at the end of the available columns list some properties with [X] that denote these extended custom columns of yesteryear. You can filter them by name so you only see the columns you want (e.g. artist). Moreover all these properties can be used to search and filter documents, e.g. find all files with SVN status=modified using xplorer˛ omni-finder.

Download 32 bit xplorer˛ (1.8 MB)
Download 64 bit xplorer˛ (1.9 MB)

I imagine most people would prefer the 32 bit version as the custom column handlers you find are mostly 32 bit DLLs and will only work in a 32 bit xplorer˛. I hope that all these abandoned projects will now be revitalized. Please spread the word and remember that you saw it here first!

4. Stranger than paradise
Here are a few sample useful column handlers that now work in windows 7/vista with the new xplorer˛.

  • Tortoise SVN. My favorite version control system.
    NOTE: The latest TSVN versions do not register the column handler. In order to see SVN columns like SVN Status and the like you need a registry tweak as explained here

  • Audioshell. Popular ID3 tag editing extension for your music collection.
  • Folder Size. Show total folder sizes in a column (this is also available in xplorer˛ natively)
  • EXIF details. If somebody has to recommend one for camera/picture data I will add it here <g>

Basically all your favorite column handlers that used to work in windows XP are back. Just install them and xplorer˛ will pick up the columns. If you are a programmer with an abandoned column handler project please consider continuing its development. I am sure many 3rd party file managers will follow xplorer˛'s example.

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