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.

event.target.setSelectionRange(...event.detail.selRange);
            },
            charLimit: event => {
              const { charLimit } = event.detail;
              const { target } = event;
              if (charLimit === 0) {
                target.removeAttribute("maxLength");
                return;
              }
              target.setAttribute("maxLength", charLimit);
              let value = elementData.userValue;
              if (!value || value.length <= charLimit) {
                return;
              }
              value = value.slice(0, charLimit);
              target.value = elementData.userValue = value;
              storage.setValue(id, { value });
              this.linkService.eventBus?.dispatch("dispatcheventinsandbox", {
                source: this,
                detail: {
                  id,
                  name: "Keystroke",
                  value,
                  willCommit: true,
                  commitKey: 1,
                  selStart: target.selectionStart,
                  selEnd: target.selectionEnd,
                },
              });