About the Visual C# Express Editor limitation

The unity environment doesn't allow you to use Visual C# Express 2008 as the external editor, saying it can't be handled from outside. I was wondering if this is a legal/license limitation or a technical one.

If it is a technical limitation, I found this workaround by using DDE: 1) download ClassExec from http://fvue.nl/wiki/ClassExec 2) Create a batch file (I used runvc.bat) in the same directory where you opened ClassExec, and put in the following contents :

classexec %1 --class .cs

3) Associate the batch file as your external editor in unity. 4) If Visual C# Express is open in the background and has the sync'ed solution open, when you double click a script in the unity editor the selected file will open in the existing Visual C# window, allowing you to edit it with code completion and all the fun features.

I'm considering adding this workaround to the unity wiki, but don't want to do anything evil. Is this legal?