I've made some updates to the first version of WPF/E Pad I posted last week.  The new version has the following changes:

• Enhanced readability by lightening the background color of the XAML textarea
• Modifed the loading logic to download one XAML file at a time.  I've also added a status area in the XAML files pane to show what file is currently loading
• Added a splitter for XAML and Scene panes.  Just drag the XAML pane titlebar up or down to resize
• Added scroll wheel support for zooming

Click here to run the new version.  The new source can be found here.  The original source can be found here.