Attach (recommended) or Link to PDF file [here:] Can't see how to attach a pdf here, but it is simple to create. Add a form object textbox to a pdf and make sure the option for "Multiline" is true.

Steps to reproduce the problem:
1.  Open a document with a Textbox that is set to Multiline.
2. Attempt to hit the Enter key to go to a new line.

What is the expected behavior? The cursor goes to a new line.

What went wrong? It does not go to a new line.

Link to a viewer: It can be reproduced on mozilla.github.io/pdf.js

I corrected the issue by altering the pdf.js file like this
element.addEventListener("keydown", event => { 
[...]
--} else if (event.key === "Enter") {
++ } else if (event.key === "Enter" && !this.data.multiLine) {

Our initial testing is coming through clean, and hopefully something like this code can be committed to the project in the future.

this.container.className = "fileAttachmentAnnotation";
    const trigger = document.createElement("div");
    trigger.className = "popupTriggerArea";
    trigger.addEventListener("dblclick", this._download.bind(this));
    if (
      !this.data.hasPopup &&
      (this.data.titleObj?.str ||
        this.data.contentsObj?.str ||
        this.data.richText)
    ) {
      this._createPopup(trigger, this.data);
    }
    this.container.append(trigger);
    return this.container;
  }
  /**
   * Download the file attachment associated with this annotation.
   *
   * @private
   * @memberof FileAttachmentAnnotationElement
   */
  _download() {