A customizable editor for (X)HTML written in Tcl/Tk -- updated after HP moved
Source code has been made available at: http://wolf-dieter-busch.de/html/res/Heimatseite/download/MTEsource.zip
May 29, 2007 I'm guessing the source code linked to above doesn't work. Some of the code looks for CSS/style.css but no CSS folder exists in the zip file. It's possible there are other problems but it's hard to tell. Plus, there's no pkgIndex file or other obvious entry point to try to run the code. The screenshot sure looks nifty though.
Clicking around on the website there seems to be another link which shows more promise. The program starts up, though clicking in the window yields an error. Pity. Probably not insurmountable, but not useful out-of-the-box.
MTE (that's the name of the editor) is intended to work out of the box, but it requires that you read the help files (German, English). See section "First Steps". Hint: top right there is an option button. Care that it shows up "XML", not "Text".