Function gdk_window_get_device_position_double 

pub unsafe extern "C" fn gdk_window_get_device_position_double(
    window: *mut GdkWindow,
    device: *mut GdkDevice,
    x: *mut c_double,
    y: *mut c_double,
    mask: *mut GdkModifierType,
) -> *mut GdkWindow