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.

const elementData = {
        userValue: textContent,
        formattedValue: null,
        valueOnFocus: "",
      };
      if (this.data.multiLine) {
        element = document.createElement("textarea");
        element.textContent = textContent;
        if (this.data.doNotScroll) {
          element.style.overflowY = "hidden";
        }
      } else {
        element = document.createElement("input");
        element.type = "text";
        element.setAttribute("value", textContent);
        if (this.data.doNotScroll) {
          element.style.overflowX = "hidden";
        }
      }
      GetElementsByNameSet.add(element);
      element.setAttribute("data-element-id", id);
      element.disabled = this.data.readOnly;
      element.name = this.data.fieldName;
      element.tabIndex = DEFAULT_TAB_INDEX;
      this._setRequired(element, this.data.required);
      if (maxLen) {
        element.maxLength = maxLen;
      }
      element.addEventListener("input", event => {
        storage.setValue(id, { value: event.target.value });