Multiple CSS Classes

In function flickr_filter_split_config a preg_match_all using the regex '/([a-zA-Z]+)=([-@0-9a-zA-Z:;]+)/' appears to be used to parse the parameters passed.

The statement is

preg_match_all('/([a-zA-Z]+)=([-@0-9a-zA-Z:;]+)/', $string, $parts, PREG_SET_ORDER);

I would like to be able to pass more than one class to the filter, but when passed as

[flickr-photo:id=nnn,size=m,class=class1 class2]

only the first class is handled.

When passed as

[flickr-photo:id=nnn,size=m,class="class1 class2"] or
[flickr-photo:id=nnn,size=m,class='class1 class2']

no class information makes it through.

Is this a fixable problem or should I work on the basis that multiple classes can not be passed?

https://drupal.org/node/147152#comment-561346 seems to indicate that multiple classes should be possible, though this was posted quite a while ago.

Thanks,

Alan