Got it.
Use Format > Font > Show Fonts to bring up the Fonts dialog.
Select your text. It will be highlighted in Blue. The selected font will be highlighted in Gray in the Fonts dialog.
Click the titlebar of the Fonts dialog. The highlight in the Document window should turn Gray and the selected font in the Fonts dialog should be highlighted in Blue. That's your clue that the Fonts dialog now has the keyboard.
Now you should be able to use the up and down arrows to rapidly scroll through the fonts and see the changes in the Document window.
At least, it seems to working repeatably for me.
Good luck. I hope this helps.
August.