Wheel scroll does nothing on pages with a fixed top-left element (linkedin.com/in/<account>, behind login)

[dashn9]

Observed on Linux, driving a logged-in linkedin.com/in/<account> profile over CDP: HumanMouse::scroll / CdpMouse::wheel return Ok(()) and the wheel events are dispatched, but the page does not move.

Likely cause

CdpMouse::wheel dispatches Input.dispatchMouseEvent{type: mouseWheel} at the current cursor position:

https://github.com/dashn9/rustenium/blob/main/rustenium/src/input/cdp/mouse.rs#L249

let (x, y, buttons) = {
    let s = self.state.lock().unwrap();
    (s.position.x, s.position.y, s.buttons)
};

That position starts at (0.0, 0.0) (input/cdp/mouse.rs:46) and is only ever updated by an explicit move (input/cdp/mouse.rs:119-120). Chrome applies a wheel event to the scroll container under that point — so until something has moved the pointer, every scroll is aimed at the very top-left pixel of the viewport.

On a LinkedIn profile that pixel sits under the fixed global nav bar, which is not a scroll container, so the wheel is delivered and correctly does nothing. Any page whose top-left corner is a fixed or otherwise non-scrolling element should reproduce it; a plain document scrolls fine, which is why this does not show up in ordinary use.

Nothing in that path is platform-specific, so it may well reproduce off Linux too — Linux is just where it was hit.

Repro

1. Open a logged-in linkedin.com/in/<account>.
2. Call human_mouse().scroll(600, 0, &context) without moving the pointer first.
3. Page does not move. window.scrollY stays 0.
4. Move the pointer into the page body first, then scroll again — it moves.

Suggested fix

Aim the wheel at the middle of the viewport rather than at the last known pointer position when nothing has moved the pointer yet — or let MouseWheelOptions carry an explicit point. Defaulting the initial position to (0, 0) is the part that makes an untouched session scroll at a corner nobody meant.

Related but distinct: #9 is about the end of a scroll snapping back; this one is about the scroll never applying at all.