Concise Oxford Dictionary says
///The word queer was first used to mean ‘homosexual’ in the late 19th century; when used by heterosexual people, it was originally an aggressively derogatory term. By the late 1980s, however, some gay people began to deliberately use the word queer in place of gay or homosexual, in an attempt, by using the word positively, to deprive it of its negative power. Queer also came to have broader connotations, relating not only to homosexuality but to any sexual orientation or gender identity not corresponding to heterosexual norms. The neutral use of queer is now well established and widely used, especially as an adjective or noun modifier, and exists alongside the derogatory usage///