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 
this.linkService.eventBus?.dispatch("dispatcheventinsandbox", {
                source: this,
                detail: {
                  id,
                  name: "Keystroke",
                  value: elementData.beforeInputValue,
                  change: event.data,
                  willCommit: false,
                  selStart,
                  selEnd,
                },
              });
            });
          }
          this._setEventListeners(
            element,
            [
              ["focus", "Focus"],
              ["blur", "Blur"],
              ["mousedown", "Mouse Down"],
              ["mouseenter", "Mouse Enter"],
              ["mouseleave", "Mouse Exit"],
              ["mouseup", "MouseUp"],
            ],
            event => event.target.value
          );
        }
      }
      if (blurListener) {
        element.addEventListener("blur", blurListener);