In the following spots a "MouseUp" eventName is being used, which does look inconsistent considering that the "Mouse Down"/"Mouse Enter"/"Mouse Exit" eventNames all have a space in them.
Is this inconsistency actually expected, or is it a simple typo? If the former, then a comment explaining *why* would be appropriate; otherwise we should just fix this :-)

 - https://github.com/mozilla/pdf.js/blob/25b84ce84c95ba06d1ee57e578672048269c39c1/src/display/annotation_layer.js#L806

 - https://github.com/mozilla/pdf.js/blob/25b84ce84c95ba06d1ee57e578672048269c39c1/src/display/annotation_layer.js#L945

 - https://github.com/mozilla/pdf.js/blob/25b84ce84c95ba06d1ee57e578672048269c39c1/src/display/annotation_layer.js#L1034

 - https://github.com/mozilla/pdf.js/blob/25b84ce84c95ba06d1ee57e578672048269c39c1/src/display/annotation_layer.js#L1168

/cc @calixteman 
setTimeout(() => event.target.focus({ preventScroll: false }), 0);
            },
            userName() {
              
              event.target.title = detail.userName;
            },
            hidden() {
              event.target.style.visibility = detail.hidden
                ? "hidden"
                : "visible";
              storage.setValue(id, { hidden: detail.hidden });
            },
            editable() {
              event.target.disabled = !detail.editable;
            },
            selRange() {
              const [selStart, selEnd] = detail.selRange;
              if (selStart >= 0 && selEnd < event.target.value.length) {
                event.target.setSelectionRange(selStart, selEnd);
              }
            },
            strokeColor() {