Function push_window_command 

pub fn push_window_command(command: WindowCommand)

Enqueue a window-management command from UI code (e.g. a title-bar button’s on_press). The runner drains the queue after event dispatch and applies each command to the OS window. Lives in a thread-local so it works from any widget closure without threading a window handle through the tree; each surface owns its own queue (activated via WindowCommandContext), so commands never cross windows.