I was working with a very large outline and had scrolled to the bottom of the page. I wanted to move back up the page so I used the page up key several times. I discovered that the text of the headline that I had selected was gone.
I expected to be able to scroll up the page using the page up key with no changes to my outline.
Using the page up key deleted text of the selected headline.
Upon further testing all the page navigation keys (up, down, home and end) delete text on the selected headline.
To test create an outline with several headlines with some text. Select one of the headlines. Hit any of the page navigations keys (up, down, home or end).
I'm using Mac OS X and Chrome.