Mike Harsh  has updated his WPF/E Pad. The new version has the following changes:
I put a modified version online at http://frankfurt.schwarz-interactive.de/  with a additional changes that allows you to save the files. See the save bottom in the lower right corner.
There are still some bugs inside like when you change the size of the XAML pane, but this should be fixed in the next days.
The original source code of the WPF/E Pad can be found here .