Who is the protagnist and the antagonist in The Glass Menagerie?

I think that this is a very difficult question to answer. 
I am not certain that there is one specific protagonist or antagonist in the drama. 
Part of what makes Williams' dramas so compelling is that there are no really simple
answers to anything because of human consciousness being so complex and incapable of
reduction to a singular element.  This play is no different.  Certainly, I think that an
argument could be constructed that Tom is a protagonist, as we begin to understand the
elements that set up the play through his narration.  We also tend to understand the
dynamics of the family through his perception.  Yet, if we accept this, then we also
have to accept the fact that Tom is not the type of protagonist that we can fully
embrace or admire because of his own emotional frigidity and frail nature.  While he has
physically left, his emotional compass is still discombobulated.  If Tom is the
protagonist, then we would probably say that Laura is the antagonist.  Yet, we also have
to concede that our antagonist is probably more loyal from a moral standpoint because
she stays while Tom leaves.  The dynamic between both of them might cause this
configuration to be considered in terms of protagonist and antagonist.  I would also
toss out there that Laura could be considered to be the protagonist.  It is her life
that is the center of so much discussion between brother and mother, her collection from
which the play derives its title, and she represents the fundamental glue of the
family.  When mother and brother fight, she strives to make the peace.  The play ends
with her blowing out the candles of her own birthday cake, causing the audience to see
her life as the center point as the lights dim.  I think that Laura has a claim to being
a protagonist, as well.