'standing at the window' is a correct phrase in written English.
It can be used to describe someone's physical position. For example, "John was standing at the window, admiring the view."
Me: "Mom, why are you standing at the window?" Mom: "Life is beautiful".
Several hours later, she found herself standing at the window without knowing how she got there".
He saw his parents standing at the window of the homecoming dance.
Standing at the window, peering out, I'm wondering if the rain will ever stop.
I love standing at the window, looking out to the garden.
I couldn't resist standing at the window and watching it all unfold.
Barney was especially afraid when he noticed, through binoculars, what he described as several humanoid figures standing at the windows of the mysterious craft.
America, in contrast, is standing at the $2 bettors' window.
The old woman was standing at the upstairs window, her hand pressed flat against the glass.
Henry Perowne is standing at the bedroom window of his smart London home.
They're standing at the kitchen window, looking out at the old ballbearing plant.
