** What is the "size" of the description area **
What size did you make it? All event fields are customizable using the "Customize Events" administration template section. The documentation may tell what the default size of it it is if that's what you're interested in knowing.
** the description without it "collapsing" into a paragraph? **
If you mean retain line breaks in text which is entered into a field, there's a couple of messages dealing with that subject in the 'Links' section of the Unofficial CalendarScript - Mods and Plugins site.
Every one should look around the information that available there before the site disappears from lack of support.
JMO
Dan O.
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