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.

let container = this.container;
    if (this.quadrilaterals) {
      trigger = trigger || this.quadrilaterals;
      container = this.quadrilaterals[0];
    }
    
    if (!trigger) {
      trigger = document.createElement("div");
      trigger.className = "popupTriggerArea";
      container.append(trigger);
    }
    const popupElement = new PopupElement({
      container,
      trigger,
      color: data.color,
      titleObj: data.titleObj,
      modificationDate: data.modificationDate,
      contentsObj: data.contentsObj,
      richText: data.richText,
      hideWrapper: true,
    });
    const popup = popupElement.render();
    
    popup.style.left = "100%";
    container.append(popup);