If tish'a b'av were to fall on shabbos, would the sections of Torah prohibited for study on tish'a b'av cause the seforim in which they are found to be muktze? If in a given sefer there are prohibited sections together with permitted sections of study (e.g. a nach) then I assume the permitted material would not make the entire sefer muktze since one can read it on tish'a b'av. Also, if such seforim are muktze, which category or categories of muktze would they be and why?
When shabos came in it was not muktze because it was permitted to use it. Then it can't become muktze unless it changed to a different shape.