[HelloSupport]

In the sample project (see test1.gif), I create a rectangle.   In test2.gif I run the app.  Notice that the rectangle is fully displayed.   In test3 I use the mouse scroll wheel to expand the rectangle so that it does not fit on the screen.  I would like to now horizontally scroll to see uncover the hidden part of the rectangle.  How do I do this?  The ScrollViewer that I included in the XAML does not help.    Thanks for your help.