We've actually made a change here in XF 1.5 to fix this in MG 1.1.
This is something that could be generally useful for developers.
We've added some code in discussion.js which does two things:
1) If an element has a class of 'NoSelectToQuote' and the select to quote has begun and ended within that element, select to quote can't be triggered (this specifically solves the specific example in your test post).
2) If the quoted HTML contains an element with the 'NoSelectToQuote' class, that is stripped completely from the output.
Specifically in terms of the Gallery, we've added the 'NoSelectToQuote' class to the GALLERY bb code container.