One development that did not gain much attention, but that I do feel is important here, is the Victory Over AIDS Flag:

The added stripe was meant to represent queer people who have been lost to HIV/AIDS. It was likely chosen because it is a colour of mourning.

There doesn't seem to be any consensus about who made this flag or when exactly it was used (possibly the 1980s??), but a story attached to it, which may or may not be true, is that Leonard Philip Matlovich, a gay war veteran, suggested that when a cure for HIV/AIDS was discovered, then people could cut the black stipes off their flags and ceremoniously burn them in Washington DC.

The relevance of this flag is that in the later Progress Pride flag, a black stripe is used to represent people who died from AIDS.