Well I didn't expect to get this done so fast, but I did. You can now tab or untab multiple lines of text inside Regex Hero by hitting tab and shift+tab on your keyboard. It works pretty much the same way as it does in Visual Studio. Here's a video demonstration: I didn't make this very clear in the video, but the size of the tab seems to be outside of my control. I'm hoping to find a way to fix this when I upgrade to Silverlight 3 or 4.