On the question Do 1/2 size violins sound at normal pitch? I found out that 1/2 violins are actually ~86% of a full size violin.

What do the fractions 7/8, 3/4, 1/2 etc for violin sizes represent, if they don't represent the body size or the scale length of the instrument?


Question: Is it better to put "Preview" on an iFrame with a specific height or just show it in full?
Answer: It sounds like you are describing every help widget of 10 years ago. It would be best to abandon the iframe for loading content in this manner. Definitely don't open a new window for the content either unless it's a file. There are more benefits to providing stateless url driven content, the two biggest being:


SEO
Bookmarking


You could avoid long content by providing a "read more" or "continue reading" link.


http://www.smashingmagazine.com/2009/07/28/designing-read-more-and-continue-reading-links/