Function placement 

pub fn placement(window: Rect, theme: &Theme) -> (Point, f64)

Where the palette’s card stands in window, the part of the window it belongs to under the window’s bar: its top-left corner and its width. Centred across the window, a little below its top, and never wider than the window, so a palette of an app in a window narrower than the screen stays inside that window. A compact window gives it its whole width less the standard insets, from just under the bar.