Struct WindowMeta 

pub struct WindowMeta {
    pub id: u32,
    pub output: AtomicU32,
    pub placed: AtomicBool,
    pub parked: AtomicBool,
}

Per-window bookkeeping carried in the window’s user-data map: a stable numeric id the Python side addresses the window by, the display id of the output it is placed on, and whether that output has been chosen yet.

Fields

id: u32

output: AtomicU32

placed: AtomicBool

Set once the first commit has picked the window’s output. The choice cannot key off xdg’s initial_configure_sent: a client that negotiates xdg-decoration (every wlroots-based nested compositor, GTK and Qt) is answered with a configure before it ever commits, which would leave every window on the pointer’s output.

parked: AtomicBool

Set while the window is mapped outside every output, tagged to the output it will take once one exists. See park_window.