Some things affect only 'mundane' or 'nonmagical' items. For example, the spell Quench automatically puts out nonmagical fires, but it requires a dedicated casting to put out a magical fire that isn't a spell effect (and then just for 1d4 hours). Similarly, Shrink Item affects only nonmagical objects and Shatter can be used as an AoE attack v.s. stacks of nonmagical porcelain but magic porcelain dolls require a casting each for their destruction.
The issue here is that I'm unsure what counts as 'nonmagical'. It's clear, for example, that bonafide Magic Items from the Magic Items sections of the various rulebooks don't work, and that the stuff you make with minor creation does. I'm not sure, however, if the subject of a light spell, or a Melf's Acid Arrow spell, or a shrink item spell, or continual flame, etc counts as not nonmagical while an ongoing spell persists. I've always played that merely being the target of a spell did not make something not nonmagical, but upon consideration, I'm not sure if that should definitely be the case or if that's just the interpretation of the rules that was most natural to us.
When an otherwise unattended, nonmagical object is subject to a spell with a duration, is it still an unattended, nonmagical object? What do the rules say on this matter?
Note that I'm specifically talking about things being or not being nonmagical; do not take for granted that something that is magical is not nonmagical or vice versa. That may be the case, but if so you need to support that assertion in your answer with rules-text; frequently terms like that in 3.5 don't work quite the way we'd expect them to in terms of opposites.