Explorer scroll bar pointer isn't captured when it enters a webview

[Tyriar]

Repro:

1. Open a webview
2. Drag explorer scroll bar into webview, it ignores the events

Possible fix is to set/release pointer capture. Might be an issue in webviews?

[joaomoreno]

Precedence: #94055, with fix 18b8ef0

@rebornix Wasn't your fix intended to fix this problem for all webviews?

[Tyriar]

@rebornix the pointer capture thing is how I solve this to allow continued listening to pointer events from within the webview even when the pointer is outside, so if that works it'll probably be more reliable than a cover element approach.

[mjbvz]

@Tyriar I haven't used the pointer capture api but on this case, we would want to set pointer capture on the scrollbar element, right?

/cc @alexdima Since I believe you implemented scrolling

[alexdima]

@Tyriar What exact DOM API are you using? At https://mdn.github.io/dom-examples/pointer-lock/ I get three undesirable behaviors:

• My mouse cursor becomes invisible
• A browser message shows up saying I can press Escape to exit this mode
• Escape is not dispatched to the DOM but is eaten up to exit this mode

[Tyriar]

@mjbvz yes.

@alexdima oh, I didn't know it would be ambiguous, here's what I do:

addDisposableDomListener(container, 'pointerdown', e => {
  container.setPointerCapture(e.pointerId);
});
addDisposableDomListener(container, 'pointerup', e => {
  container.releasePointerCapture(e.pointerId);
});

[mjbvz]

@alexdima I believe you were looking at the pointer-lock api which is different than the pointer capture api that @Tyriar was proposing: https://developer.mozilla.org/en-US/docs/Web/API/Element/setPointerCapture