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.

if (pin) {
      this.pinned = true;
    }
    if (this.hideElement.hidden) {
      this.hideElement.hidden = false;
      this.container.style.zIndex =
        parseInt(this.container.style.zIndex) + 1000;
    }
  }
  /**
   * Hide the popup.
   *
   * @private
   * @param {boolean} unpin
   * @memberof PopupElement
   */
  _hide(unpin = true) {
    if (unpin) {
      this.pinned = false;
    }
    if (!this.hideElement.hidden && !this.pinned) {
      this.hideElement.hidden = true;
      this.container.style.zIndex =
        parseInt(this.container.style.zIndex) - 1000;
    }
  }
}
class FreeTextAnnotationElement extends AnnotationElement {