Function event_offset 

pub fn event_offset(
    event: &WindowEvent,
    offset: Vec2,
    scale_factor: f64,
) -> Cow<'_, WindowEvent>

event as a widget drawn offset (logical pixels) from where it is laid out meets it: a pointer or touch position moved back by offset, so content on its way (a band disclosing above it, a pane gliding) is hit-tested where it is drawn (motion::Pose::to_local). Every other event, and any event at a zero offset, passes through untouched.