"He's being polite."
thats the point. hes bein polite...to a beautiful woman. hes also bein very rude to his wife. in 2 seconds you know from one gesture, as much about his marriage as you would take 3 paragraphs to describe. remember in screenwritin a gesture like that is measured and has meanin. its not fluff. if its not there for a reason it almost shouldnt be there (with exception of course).
but most peeps when they ask about subtext are askin about subtext in dialogue. i think hamboogul's eg was good cos not everyone realizes theres subtext in actions.
anyway subtext in dialogue i think means sayin a lot without comin right out and sayin it. or by sayin very little.
like in the john malkovich directed "the dancer upstairs" adapted from a graham greene novel, javier bardem is a police inspector and the dudes talkin to a woman hes met durin his investigations, and he tells her before he was 5-0 he was a laywer. and she asks him how come he changed jobs. and he just sez, "im tryin to find a more honest way of practicin the law."
hes not all, "yea i was tired of the bullshit corruption and the injustices i witnessed everyday and the peeps i couldnt help cos the only justice that prevailed in courts were the kind you could afford and finally i had enough and i told my boss to go f*ck himself and quit."
nope.
"im trying to find a more honest way of practicin the law." he didnt need to say more, you got everythin.
anyway hope this answers your ?. this sorta thing you cant just learn and apply, cos you really hafta sorta get it first. i guess you get it by writin it and seein if it sticks. or stinks. :thumbs