Sample text preview pane is placed in the top of Fonts Pane .
Here you can type your text for Font Samples preview or press sample text button to get menu with some defined samples.
You can set as preview text any Unicode character from character map or you can change keyboard layout for different languages.
Press filter button if you want to preview only fonts which support current keyboard layout.
If you close Sample Text, it's available again from main menu ViewSample Text panel.